The Lives of Fungi pdf download

What all of these living organisms have in common, though—indeed, what every living organism on this planet has in common—is a reliance on fungi. Yet even though fungi are all around us, they remain poorly understood. With our planet and natural resources under constant assault from an ever-shrinking habitat and a burgeoning human population that brings with it pollution, invasive species, and other manmade disasters, it is becoming increasingly important that we are aware of the natural treasures that exist all around us.

Mushrooms and other fungi are beautiful and interesting organisms, which I know is an opinion that is not shared by everyone. If considered at all, fungi are often seen as mere recyclers of nutrients and decomposers of organic matter in the environment— rotters of the once-living. However, recently developed methods to detect organismal DNA from the environment, improved microscopic techniques, and novel methods for culturing and cultivating,

THE LIVES OF

FUNGI

THE

LIVES

FUNGI OF

A NATURAL HISTORY OF OUR PLANET’S DECOMPOSERS

Britt A. Bunyard

PRINCETON UNIVERSITY PRESS

PRINCETON AND OXFORD

Published by Princeton University Press 41 William Street, Princeton, New Jersey 08540 99 Banbury Road, Oxford OX2 6JX

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CONTENTS


INTRODUCTION	PATHOGENS, PANDEMICS,
	AND SCOURGES
WHAT ARE FUNGI?
	MUTUALISTIC SYMBIONTS
REPRODUCTION
	FUNGI AND HUMANS
CHEMISTRY AND PHYSIOLOGY
	FUNGI AND THE FUTURE

SAPROBES AND PARASITES

Glossary

Useful resources Index

Acknowledgments

INTRODUCTION

“Everything depends on everything else.”

(Translated credo of the Haida people of the Pacific Northwest)

l life on the planet is connected, but these	hormonal control of the plant, determining its
connections go mostly unseen. As you read this,	drought resistance, heat resistance, and toxin production
for example, microbes covering much of the	in response to attack by pathogens or herbivory.
surface of your body—inside and out—are going about	Mycorrhizae of the tree’s roots are responsible for the
their business. In fact, the vast majority of living cells that	uptake of water and nutrients. These fungi are attached
make the ecosystem that is “you” are not human; the vast	to adjacent and unrelated trees, and have fruitbodies
majority are microbial, and some are fungal.	that host fungi-eating (mycophagous) arthropods. These
It’s a similar story with the tree outside your	arthropods are in turn parasitized by nematodes, or by
window, which is mostly of non-living tree cells; most	smaller arthropods, such as braconid parasitoid wasps.
of the living cells making up that tree are probably not	Those tiny parasitoid wasps rely on viruses to mask
tree or even plant cells. Endophytic organisms inside	their invading parasite egg from the immune system
the plant’s tissues are responsible for much of the	of the host’s larva, and so the connections go on.

are showing that fungi are much more ubiquitous than we thought. They are

Favolaschia calocerais a beautiful

rotter of wood that has recently been

also revealing that fungi are much more important to the environment and,

turning up in many new places and

by extension, to ourselves.

new habitats. A changing climate

and international travel and trade are

Based on sheer mass and the number of species, fungi (along with insects)

changing the mycological landscapes

around us.

are likely the most common and most evolutionarily successful organisms on

the planet. Fungi can be found thriving on all continents of Earth, from the

Mushrooms are the reproductive

loftiest peaks to the driest deserts, from the depths of the world’s oceans to

structures of fungi and come in a

our own backyards. Nor do they stop at our doors—they can be found thriving

bewildering assortment of shapes

and forms. The Common Splitgill

(to the chagrin of most) within our own homes. With advances in modern

(Schizophyllum commune) is one

of the most ubiquitous of all mushrooms,

microscopy we have come to know that molds and other fungi are found in

found on dead wood of every continent

just about every niche in the environment and that probably no plants—long

except Antarctica.

considered the keystones of all habitats—can thrive for very long without their

fungal partners. Obligately intertwined among roots	As a species, we humans have come to a crucial
as mycorrhizae, growing epiphytically on plant surfaces,	point in our history. About 2.5 billion people inhabited
and found within plant tissues as endophytes, fungi are	our planet when I was born, but by the early 1990s,
the true puppet masters in nature. Conversely, fungi	when I was a graduate student studying mushrooms
also cause the vast majority of disease among plant	and other fungi, our population had increased to 5.3
species, including those to which we owe our very	billion. Now that number is 7.8 billion, which is
survival as sources of food, fiber, and medicines; again,	projected to rise to 9.7 billion by 2050. These snowballing
fungi pull the strings.	figures highlight the immense challenges we face when

tackling global climate change and figuring out how, as a species, we can sustain the healthy ecosystems that we depend on for our existence.

There is no doubt that fungi will play an important role in this process, as humans have collected, used,

س Fungi come in a tremendous array

and eaten mushrooms and other fungi for (arguably)

of colors, their forms and shapes range

from very simple to complex, and at

as long as we have been human—most likely longer.

times otherworldly. Their ecology and

Today, wild forest mushrooms are harvested on every

roles they play in the environment are

every bit as diverse.

continent except Antarctica, and many species can be

cultivated with relative ease. However, the most	of magic as mushrooms emerge from the forest floor.
abundant edible mushrooms are ectomycorrhizal,	Their amazing hydraulic strength betrays their
which means that they symbiotically interact with	presumed delicate mien as they push up debris and
tree roots. These species have sufficient ongoing	duff. One by one, their caps mature and open to release
supplies of nutrition from their tree hosts to support	innumerable spores to the vagaries of the slightest
abundant annual fruiting, but forests around the world	breeze. There is no telling where those spores will
face tremendous pressure for other uses. This often	alight, but if the conditions and substrate are favorable,
results in deforestation or degraded forest ecosystems,	the cycle will begin anew. But the mushroom is just the
with a direct impact on the fungi they host.	mycological tip of the iceberg, as the main body of the
Yet as crucially important as they are to the planet,	fungus remains hidden. Moreover, the fungi that produce
we pay the average fungus almost no attention as it	macroscopic fruitbodies—mushrooms that are large
goes about its business, even though fungi do things	enough for you to notice—form just a tiny fraction
and live in ways that would seem otherworldly to most	of all the fungi. So just what are fungi? What are they
people (some fungi do things you probably could not	up to and what are they doing in the environment?

imagine). Sometimes, though, if the conditions are just right, and you happen to be at exactly the right place at exactly the right time, you might witness a moment

INTRODUCTION

What are fungi?

Fungi comprise an entire kingdom of life, and just as members of the animal or plant kingdoms are very different from one another, so are members of the fungal kingdom. Their ways of obtaining nutrition, their defense mechanisms, genetics, reproduction, communication, and so on, are very different to the animalian ways that are familiar to most people.

WHAT ARE FUNGI?

For most of scientific history, fungi were considered to be plants. Beginning with Aristotle, all living things were treated either as plants or as animals, depending on whether they could move or not. The system of

classification that we use today—with ranks of

شCordyceps militarisin cultivation.

relatedness such as kingdom, phyla, genera, and so on—was developed by Carolus Linnaeus in the eighteenth century. However, although it is more sophisticated, it didn’t much change things for fungi, which were still thought of as plants. So it is more than a little ironic that today, with a much better grasp of the evolutionary relatedness of all life on the planet, it turns out that the organisms most closely related to fungi are not plant, but animals (including us).

If you encountered a mushroom in your local woods, you would of course recognize it. Likewise, holding a green leaf in your hand you would know that it came from a plant. But the vast majority of fungi do not make mushrooms, and what if the plant material were not green? How would you then know what you were looking at? For that matter, how is life classified? To answer such a fundamental question, you have to know a bit about biology and physiology.

The first rule of biology is that living things are made of cells; the cell is a collection of all the materials needed to conduct the life of that organism, contained within a semipermeable phospholipid membrane. However, as simple as this sounds, not all biologists agree—according to this definition, a virus would not be a living entity, but some scientists would argue otherwise.

At the simplest level, all life is divided into Prokaryotes and Eukaryotes. Prokaryotes are singlecelled organisms (which include bacteria) that lack membrane-bound organelles and do not have a nucleus, and their DNA consists of a single, circular chromosome. In addition to a cell membrane, bacteria may or may not have a rigid cell wall, but that’s about it.

INTRODUCTION

In comparison, Eukaryotes are far more	fungus strength and flexibility. Chitin is somewhat
organized from a physiological standpoint. They feature	similar to the cellulose found in plants, but is made of
membrane-bound organelles, such as mitochondria	long chains of carbohydrates that are connected by a
and a nucleus, and DNA that is organized as complex	different specific chemical bond. In addition to fungi,
chromosomes. Eukaryotes include single-celled protists,	chitin is found in the exoskeletons of insects and other
plants, animals, and fungi.	arthropods; the group of protists most closely related to
Fungi derive their energy from all heterotrophic	fungi also has cell walls of chitin.
means imaginable—and probably some fungi do things	Humans do not produce chitinases, which are the
you could not imagine. Perhaps most fungi are parasites, enzymes needed to degrade chitin. A popular
and it is likely that all plants have species-specific fungal	misconception is that because fungi are composed of
pathogens; many of our agricultural crop varieties have	chitin, they're indigestible and not nutritious. However,
variety-specific fungal pathogens. Other fungi are	although it is true that there is little nutrition to be had
saprobes (deriving their nourishment from	from chitin (or plant cellulose for that matter), there is
decomposing dead organic matter), while some are	plenty else within the cells of fungi and plants that is
mutualistic symbionts of other organisms, especially	nutritious. Also, the chitin we ingest when we consume
plants. A few fungi are carnivorous, trapping and killing	mushrooms and other fungi passes through us as fiber,
their animal prey as a source of nitrogen.	in much the same way as plant cellulose. While it is
What all fungi have in common, though, is cell	indigestible, fiber has a beneficial role in our diets.

walls composed of chitin, which gives the body of the

ر Stinkhorns like Aseroë rubra, may

look like some form of extraterrestrial life but are highly specialized for spore production and entice insects to do much of the work for them, in a similar fashion to insect pollination of plants.

ز Fungi are not always mutualists with insects. Beauveria bassiana and Metarhizium anisopliaeare entomopathogenic (insect-killing) fungi and shown here on Red Palm Weevil (Rhynchophorus ferrugineus); by way of comparison, an uninfected specimen is shown in the center.

WHAT ARE FUNGI?

FORM AND FUNCTION	However, a similarity of fruitbody forms can
Fungal reproductive structures come in a wide array	be misleading and has led mycologists to disagree on
of sizes, shapes, and colors, but fruitbodies that are large	classification schemes in the past. As a fascinating result
enough to be called mushrooms are produced only by	of convergent evolution, ascomycete and basidiomycete
ascomycetes and basidiomycetes. Common fruitbody	fungi feature species that produce similar-looking
forms are often grouped as fruitbodies with gills, pores	mushrooms, such as cups, clubs, and truffles.
or tubes, teeth or spines (agarics and boletes); shelf-like	Convergent evolution has driven groups within a
mushrooms with pores or gills (polypores); bird’s nest	phylum to produce similar looking forms as well. Thus
and cup fungi; puffballs and puffball-like fungi; jelly fungi;	we have several orders within the basidiomycetes that
coral and club fungi; and truffles and truffle-like fungi.	produce shelf-like fruitbodies, but not all of them are

polypores. It is the environment and natural selection that drives the organism into a best fit for its situation,

س Mushrooms often take on beautiful

which is why we have many groups of basidiomycete

forms, sometimes resembling other

fungi that produce truffle-like forms—this type of

organisms, like this coral mushroom,

Ramaria stricta.

fruitbody is most suited to life in arid environments.

WHAT ARE FUNGI?

Diverse forms for reproduction	CROSS-SECTION
Fungi and fungi-like organisms	CROSS-SECTION

produce reproductive structures in a wide array of sizes, shapes, and colors. Common forms feature gills, pores or tubes, teeth or spines; may be shelf-like with pores or gills; cup-shaped, coral or club-shaped; amorphous oozing or jelly-like; or round and spherical like a ball. Many tiny molds form no fruitbody at all, and simply create reproductive propagules from conidiophores.

CHANTERELLES

FALSE MORELS

TRUE MORELS

			CROSS-SECTION
		CROSS-SECTION
EARTH STARS	STINKHORNS	PUFFBALL	BOLETES
SIMPLE CONIDIOPHORES	SIMPLE CONIDIOPHORES	OOZING PLASMODIUM	CUP FUNGI

CORAL FUNGI

GILLED FUNGI

TEETH FUNGI

POLYPORES

THE FUNGAL FOSSIL RECORD	the chytrids and higher fungi split from a common
Although soft fleshy fungi do not fossilize very well,	ancestor. The first taxonomically identifiable fungi
we do have a fossil record for them. The first fungi	are from 460 MYA, and seem similar to modern
undoubtedly originated in water, like much of the	Glomeromycota. At about 400 MYA is when the
earliest life on Earth. Based on the fossil record,	Basidiomycota and Ascomycota split from a common
fungi are presumed to have been present in the	ancestor. The first insects came on to the scene around
Late Proterozoic, 900-570 million years ago (MYA),	MYA; the first beetles and flies date to around
and maybe further back than that; the oldest “fungus”	MYA.
microfossils were found in Victoria Island shale and	Much of what we know of no-longer-extant
date to around 850M-1.4B years old, although the	fungi comes from specimens found in amber. Due
jury is still out on whether they are truly fungal.	to the preservative qualities of the tree resin, amber is
Whatever the precise date, the consensus seems to be	one medium that preserves exquisite detail in delicate
that fungi probably arrived on land just ahead of the	objects such as fungal bodies. Not only does the resin
first terrestrial plants (which date to around 700 MYA),	prevent air from reaching the fossils, but it also
and paved the way for plants to move from a marine	withdraws moisture from the tissue, resulting in a
environment to ever-drier habitats.	process known as inert dehydration. Furthermore,
The first “lichen-like” organisms we see in the fossil	amber possesses antimicrobial compounds that kill
record date to around 600 MYA, and around 550 MYA	any microorganisms that would decay organic matter,

WHAT ARE FUNGI?

naturally embalming anything that gets trapped. Because of these properties a few fossilized mushrooms have been preserved beautifully in amber that dates from the Cenozoic and Cretaceous periods. The oldest mushroom is Palaeoagaricites antiquus(100 MYA), which resembles modern-day members of the family Tricholomataceae, while other species include Archaeomarasmius legettii(90 MYA), Protomycena electra (20 MYA), and Coprinites dominicana(20 MYA). The latter three all look pretty much the same as mushrooms you can find in woods today.

Mycorrhizal relationships are believed to have arisen more than 400 MYA, as plants began to colonize terrestrial habitats. These relationships are seen as a key innovation in the evolution of vascular plants. Recently, the first fossil ectomycorrhiza associated with flowering plants (angiosperms) was discovered. The fossils were found in a piece of Lower Eocene (52 MYA) Indian amber, from a time only 13 million years after the demise of the dinosaurs. Mycorrhizas are extremely rare in the fossil record.

ص As discussed in the text, amber preserves entombed organisms exquisitely. Although very few fossils of mushrooms are known, organisms that feed on fungi are frequently found in amber, such as this mycophagous phorid fly.

μm

ز The oldest known fungal fossil is Ourasphaira giraldaefound in shale that formed between 900 and one billion years ago in what is now the Northwest Territories of Canada. Despite its age, the fossils are very well preserved. Spores of the fungus, clearly visible, are less than a tenth of a millimeter long and connect to one another by slender, branching hyphal filaments.

INTRODUCTION

CLASSIFICATION AND TAXONOMY	simplified, this taxonomic scheme is still a pretty
At the time of writing there are around 100,000 species	useful system when it comes to understanding
of named fungi, although it has been estimated that	what these fungi are and how they reproduce.
there are probably more like 1.5 million species in total,	More recently developed classification schemes
meaning the vast majority of fungi await discovery and	separate fungi into additional classes (or phyla),
description. The reason for this is because fungi are	although not all scientists agree on the taxonomic
cryptic—the microscopic size of most of them makes	hierarchies for some of the oddball groups. Formal
them difficult to find, and those that elude culture often	phylum names are capitalized (Chytridiomycota,
remain unknown. However, we know there are many	Glomeromycota Basidiomycota, and Ascomycota),
unseen fungi out there because they leave their DNA	while “Zygomycota” is often represented with
behind in soil and other substrates.	quotations, as it is something of an artificial group of
The major groups of fungi have been classified	fungi that, together, are not monophyletic. Among these
according to characteristics of their sexual reproductive	groups, basidiomycetes and ascomycetes fungi (or
structures, which until recently meant that fungi were	“basidios” and “ascos” as they are sometimes referred to
grouped into four classes: chytridiomycetes, zygomycetes,	by mycophiles) are collectively known as the “higher”
basidiomycetes, and ascomycetes. Although it is overly	fungi. Other than mycologists, most people are familiar

only with the larger showy fungi of the basidiomycetes and a few ascomycetes.

However, if fungi are classified on the basis of how they reproduce sexually (the teleomorphic or “perfect” life cycle state), what happens with asexual forms (the anamorphic or “imperfect” state)? A great many fungi are known only as anamorphs, and many of these are economically important—they cause damage to our crops, rot our stored foods, or cause mycoses. Such fungi are troublesome for the taxonomists whose job it is to come up with names for them, so in the past these “imperfect” fungi were simply lumped into one big group (the deuteromycetes or fungi imperfecti), regardless of their evolutionary relatedness. More recently, though, DNA sequence analysis has enabled researchers to finally determine the teleomorphic state, and thus teleomorphic name, for any fungus, without the need to attempt to get it to produce sexual spores in culture.

ر Young oyster mushrooms

(Pleurotusspecies) are a favorite culinary mushroom and easy to cultivate.

WHAT ARE FUNGI?

Fungal Phylogeny

Modern classification schemes separate fungi into phyla Chytridiomycota, Glomeromycota, Basidiomycota, and Ascomycota, and the polyphyletic “Zygomycota” is slowly getting teased apart. The ecology of each group of fungi is also pointed out, as well as those that are motile.

	Parasites, Saprobes,		Parasites, Saprobes,	Parasites, Saprobes,
	Mycorrhizal		Mycorrhizal, Symbionts	Mycorrhizal
Parasites, Saprobes	(Endogenales)		-20% lichenized	-50% lichenized
CHYTRIDS	ZYGOTE FUNGI	Mycorrhizal	SAC FUNGI	CLUB FUNGI

LOSS OF FLAGELLA

KEY

= Former = Dikarya Zygomycota

WHAT ARE FUNGI?

ر Chytrid fungi are infamous pathogens of amphibians like this infected Pebas Stubfoot toad (Atelopus spumarius) crawling over a leaf in Ecuador.

ز Some of the strangest and least known fungi are the Microsporidia, seen here at 58,000 X magnification using color-enhanced transmission electron microscopy (TEM). Microsporidia live entirely within the cells of their hosts and have extremely reduced physiologies and genomes.

DNA sequence analysis for some imperfect	evolutionary relationships for this group. It’s unlikely
fungi has also led to some surprises. In the case of	you will spy a microsporidian on your next foray in
the Aspergillus(and this has been known for decades),	the woods, though, as Microsporidia are very tiny,
it was confirmed that more than 300 species belong	unicellular parasites of animals (mostly insects, but
to no fewer than 11 teleomorphic genera. This was	a few are known parasites of humans). The entire life
slightly problematic, as Aspergillusis an asexual name.	of a microsporidian, including replication, takes place
So, in 2012, scientists changed the rules on how things	within the cell of its host. If they came from a true
are named, making allowances for well-established	fungal ancestor, they long ago gave up hyphal growth
asexual names in cases where switching to the sexual	to live as endosymbionts. Microsporidians are some of
name would be a major headache. Consequently, some	the smallest known Eukaryotes and have the smallest
Aspergillusspecies (including notorious mycotoxin	Eukaryotic genomes.
producers such as Aspergillus flavus, A. parasiticus, and	While the microsporidians are the newest group,
A. ochraceus) retain the anamorphic name, but when	the chytridiomycetes have been long considered the
it’s preferential to use teleomorphic names, as in	most primitive of the “true” fungi. Found worldwide,
well-established sexual genera like Eurotium, Emericella,	most chytrids are saprotrophs, feeding on decomposing
and Neosartorya, those names are used instead.	organic matter, although some species are parasites of
Before we launch into a brief discussion of the	plants and animals (as you will see later in this book,
“true” fungi, it is worth mentioning the newest group	chytrids are linked to the worldwide die-off of
of fungi: the Microsporidia. Until 2006, this strange	amphibians). Chytrids are the only motile fungi,
group of tiny organisms was thought to be protist,	producing zoospores that are propelled by whip-like
but it is now considered to be extremely simplified	flagella; all fungi placed above chytrids on the fungal
primitive fungi, or possibly just the nearest relatives to	tree of life are nonmotile.

fungi—it’s going to take further analysis to clarify the

INTRODUCTION

Our next group, the zygomycetes, was always a mixed	mushrooms people are familiar with and produce
bag of fungi placed together by virtue of having	sexual spores on club-like stalks called basidia (giving
aseptate hyphae. Some well-known examples of	them their alternative name, club fungi), while the
zygomycete fungi include black bread mold (Rhizopus	ascomycetes (known as sac fungi) produce sexual spores
stolonifer), and Pilobolusspecies (the Hat Thrower),	in a special sac-like structure called an ascus. The
which are capable of ejecting spores great distances.	ascomycetes are the largest group of fungi, and include
Glomeralean (also spelled glomalean) fungi were	morels, truffles, and yeasts.
once part of the zygomycetes, but have now been	Both groups grow by hyphae with septa, although
elevated to their own phylum, the Glomeromycota.	some members grow as single-celled yeast, and they
These fungi are poorly known, as few have been seen	live as saprotrophs, parasites, or mutualistic symbionts.

or cultured. Few (if any) have sexual reproduction; they form no obvious fruitbodies; some form clusters of asexual spores, and that’s about it. We also know that

س Some of the ascomycete fungi

glomeralean fungi are mutualistic symbionts of most

produce very colorful cup-shaped

mushrooms like this pretty Sarcoscypha

plants, so they are likely the puppet masters of all life

coccinea, the Scarlet Elf Cup.

on the planet.

ز In the 1800s, German naturalist

The most recently evolved of all fungi are the

Ernst Haeckel studied and illustrated

numerous animals but a few fungi

basidiomycete and ascomycete, which share a common

impressed him as well, notably the

ancestor. The basidiomycetes include most of the

showy basidiomycetes.

WHAT ARE FUNGI?

INTRODUCTION

FUNGAL PATHOGENS

Many of the fungi on the planet today—perhaps even the majority of them—are pathogens. But as with all life, fungi also have their own parasites and pathogens. In fact, there are many fungi that are parasites of other fungi. For example, the common jelly fungus Tremella (Witch’s Butter) was long thought to be a saprobe of rotting wood, as it is often seen growing near species of Stereum(False Turkey Tail), which is another saprobe on fallen logs. However, it turns out that Tremellais a parasite of fungi like Stereum(and Peniophora).

Just like animals, fungi can be afflicted by viruses, virus-like pathogens, and even prions (scientists study the prions of yeast fungi to better understand how prions cause diseases in mammals, such as kuru of humans, scrapie of sheep, bovine encephalopathy of cattle, and chronic wasting disease of deer). Viruses are quite common in fungi and can cause economically important diseases like La France Disease in commercial mushroom farms. Fungal viruses are persistent, with transmission known to occur through anastomosis and via spores. As anastomosis occurs only between fungi of the same species (and usually the same strain), this method of transmission does not introduce viruses to new species.

In most cases, the role of viruses in the life of fungi is not known. However, in some plant pathogenic fungi the virus can act as a mutualist of the plant by reducing the effect of the pathology of the fungus. The beststudied example of this is Chestnut Blight, which is caused by the fungus Cryphonectria parasitica; when the fungus harbors Cryphonectria hypovirus, the pathology of the fungus on the plant is greatly reduced. This has

ر Witch’s Butter (Tremella

mesenterica) is commonly seen on dead wood and often presumed a saprobe. In reality, this fungus is a parasite of other fungi growing within the rotting wood.

ض Many different symbiotic organisms grow together. Each lichen is composed of several organisms, including fungi and photobionts.

WHAT ARE FUNGI?

been proposed as a method to rejuvenate the chestnut	mutualistic symbiosis that allows plants to grow in
forests that once covered most of eastern North	geothermal soils in Yellowstone National Park, USA.
America. Other examples of hypovirulence-associated	Dichanthelium lanuginosumis a panic grass that grows
viruses in plant pathogenic fungi have also been found,	in soils with temperatures of >122؛F (>50°C), but to
including in Ophiostoma ulmi, the causative agent of	grow in these warm soils it requires a fungal endophyte
Dutch Elm Disease.	(Curvularia protuberata) that is infected with Curvularia
Although not mutualists of their fungal hosts, these	thermal tolerance virus. This is a clear mutualism, as the
viruses are still beneficial for the plants that harbor the	grass cannot survive without the fungus, and the fungus
fungal pathogens. Indeed, in one instance, a fungal virus	must also be infected with the virus—without that
is an obligate partner in a complex three-way	infection, no thermotolerance is conferred to the plants.

WHAT ARE FUNGI?

THE FUTURE AND FUNGI

It’s an exciting time to be a scientist. Although we are finding out a lot of bad things about the state of our planet’s health, which can be depressing, we can take some solace in the fact that our scientific sophistication is now allowing us to see and know this. We are now able to model and predict the outcome of taking steps (or not) to reverse our course, and scientists are better able to comprehend how complex ecosystems work. We are now able to inventory all life—even that which we cannot see—before any more of it vanishes.

Subsequently, it is likely that all humans alive on the planet today are part of the most crucial century of our long history, and our decisions will dramatically impact the future of humanity and the entire living planet. However, we are not alone in facing this challenge: all life in the ecosystem is connected, and everything depends on everything else. Underpinning many of these connections are fungi, which are some of the key decomposers, pathogens, and symbionts of this world. So prepare to enter a world that is very different from the one you’re accustomed to: the (mostly) hidden world of fungi.

Mycologists (those who study fungi) have their own terminology for ways of describing fungi and their morphological features. Although this book presumes no prior scientific background, scientific terminology is inevitable in any text about natural history and living things, but do not be intimidated—a glossary at the end explains the technical terms used in this book.

ر You’ve seen mushrooms in the

environment. Once you learn about their ecology and what their role in nature is, you will see them in an altogether new light.

REPRODUCTION

Spore dispersal

Most descriptions of mushroom spore release would have you believe it is a passive affair, with spores wafting away from the fruitbody on currents of air. Once they are in the air column, spores are of course at the mercy of wafting air currents, but their initial release is far from passive. Indeed, for many fungi it is a spectacularly explosive affair.

Sordaria macrospora, an ascomycete decomposer, create very tiny fruitbodies somewhat like puffballs. However, their spores are produced in tube-like asci, and are released by a squirt gun-like mechanism.

رTrue to their name, common Pear-shaped Puffballs (Lycoperdon pyriforme) emit puffs of spores when pelted by falling raindrops. Decomposers, spores alighting on wet woody debris will germinate and begin the next generation of this mushroom.

Most of the known spore-making fungi are	as Morchella, Helvella, or Chlorociboria, asci line the
ascomycetes or basidiomycetes. Each group has its	hymenial surfaces, while in other species (Cordyceps,
own specialized way of releasing spores, but there are	Claviceps, and Xylaria, to name a few) asci are found
also a few interesting twists on spore release that merit	within chambers hidden inside the fungi.
discussion. In each case the spore-producing surface	As the fruitbody matures, liquid flows into the
(hymenium) is often constructed to dramatically	ascus, causing it to swell. Eventually the pressure builds
increase its surface area and spore production, so	to a point where the ascus tip ruptures and ascospores
fruitbodies may be convoluted, ribbed, gilled, covered	are ejected. With some large cup fungi this spore release
with tubes, branches, and so on, though some are	can be a puff that is not only easily seen, but also
simply a single smooth club.	heard—sometimes dramatically so. Once a fruitbody
	hymenium is mature and the asci are ready to fire, a
ASCOMYCETES	simple disturbance of air may be all that is necessary to
Ascomycete fungi have a style of spore release that is	get the asci to discharge simultaneously. Even the most
often likened to a squirt gun. With this group, spores	ardent mycophobe will be pleasantly surprised to watch
are formed within an elongate sac-like pouch called	as you hold a carefully picked ascocarp in front of you,
an ascus. In some species of cup mushrooms, such	blow a stream of air over its surface, and…puff!

REPRODUCTION

Cap

BASIDIOMYCETES

Gills

Basidiomycete fungi have a very different style of spore

release called ballistospory, which can be best described

Stalk

as a surface tension catapult. As this suggests, spore

Basidia

release is explosive. The spores (ballistospores) are borne on the mushroom fruitbody cap, either on the surface of gills for agarics, or on the walls of tubes for boletes and polypores. Lining the hymenial surface are specialized

hyphal tips called basidia, which have outgrowths

Gills

known as sterigma, where spores will develop.

The key to spore ejection among basidiomycetes is the production of something called a “Buller’s drop.”

Hyphae

The process starts with a small quantity of a sugary

hygroscopic liquid, such as mannitol, being released at	Basidium
the sterigma. Moisture from the air condenses on this	Mushroom anatomy
liquid and over the surface of the spore, forming a film	Although it may look simple, a
	mushroom is an amazingly engineered
of liquid on the spore’s surface and growing into a
	structure. An elongate stem supports a	Spores
droplet at the sterigma. The droplet—Buller’s drop—	cap for spore release into the air

column. Beneath the cap are many gills

that dramatically increase the hymenial grows until it reaches a critical size, at which point it

surface area. Gills are covered with

touches the water film on the spore surface and coalesces.

basidia that produce tremendous

numbers of spores. At this moment, surface tension quickly pulls the drop onto the spore: the drop collapses, and the surface energy is converted into kinetic energy, creating the necessary

Basidiomycete spore release

Shown are the sequence of events leading to ballistosporic spore ejection.

Adaxial drop

Spore

Hilar appendix

Sterigma

Buller's drop

momentum to detach the spore from the hymenial	Many others sequester the hymenium altogether
surface. Such is the energy produced that ballistospores	within a fruitbody, like a puffball or a truffle. This is
are literally blasted from their basidia, albeit for a very	also why we typically do not find aquatic ballistosporic
short distance before drag takes over and the spore	mushrooms—with one bizarre example that we will
decelerates. When the spore comes to a halt, gravity	look at in more detail later on.

over and it falls, carried away by air currents.

The key to ballistospory is the Buller’s drop, which is named after the British-Canadian mycologist Reginald Buller. However, while Buller’s drop formation requires moisture from the air, too much

سAlthough microscopic, copious

water can disrupt this mechanism altogether. For this

amounts of mushroom spores can pile

up beneath a cut mushroom cap left

reason, many basidiomycetes have fruitbodies that are

on a surface overnight, resulting in

umbrella-shaped to shield the hymenium from rain.

a spore print.

SPORE DISPERSAL

THE EFFECT OF GRAVITY	bend toward sunlight, thus more efficiently collecting
Many mushrooms can continue to release spores for	the sun’s energy on leaf surfaces.) The mushroom’s
hours and even days after being removed from their	hymenium (e.g., gills, tubes, or teeth) grow perpendicular
substrate. The cells of mushrooms taken from the forest,	to the cap, exhibiting positive gravitropism. If the cap is
and even from the produce aisle at your grocer, are still	repositioned to anything but perfectly horizontal, the
alive as long as the fruitbody is kept fresh. In fact, some	mushroom will continue to elongate and bend so that
stalked mushrooms (Amanitas, in particular) will	they will again be vertical. Shelf fungi growing from the
continue to grow, even bending upwards. Spore	sides of trees do something similar. If the tree from which
discharge only works if the mushroom cap is horizontal	they are living on is repositioned other than perfectly
to the earth, and the higher up into the air column the	horizontal (as when a standing tree falls down) a new
better to get spores carried away on air currents.	mushroom is formed horizontal to the surface. Mushroom
This growth is a direct response to gravity; the process	gravitropism ensures that the spores will be ejected from
is called gravitropism (or, sometimes, geotropism).	the gill (or tube) surface, then fall straight down without
(Similarly plants exhibit phototropism, where plants	landing on an adjacent spore-producing surface.

رVelvet Foot mushrooms (Flammulinasp.) erupt from their woody substrate and release spores.

زHorse hoof-shaped fruitbodies of Fomes fomentarius.

HOW MUSHROOMS GROW “UP”	against tiny hairs that line the inside of the otolith
The mechanism of how mushrooms grow “up” is	organ. Most of the time, the particles are uniformly
fascinating. Fungal gravitropism is a similar process to	settled telling us which way is down. If you are spun
phototropism that causes plants to bend towards a light	around or shaken like a snow globe, the particles move
source. With plants, the side of the plant stem receiving	all about giving you a feeling of disorientation, even
the strongest light sends a plant hormone signal (called	dizziness. And this is likely similar to how fungal cells
auxin) to the “darker” side of the stem, and this induces	sense gravity.
a physiological change in the cell walls there. Cells on	Within hyphal cells, nuclei probably act as fungal
the dark side of the stem release enzymes called expansins;	otoliths; their sedimentation within the cells is in
these partially break down and weaken the cell walls of	response to the direction of the gravitational forces and
dark side cells, allowing those cells to be less rigid and	tells the fungal cells which way is up. The nuclei are
to expand. Cells furthest away from the light source	enmeshed in proteinaceous actin filaments that make
receive the strongest auxin signal and expand the most,	up the cell’s internal “skeleton” (the cytoskeleton). As
thus impart a disproportionate elongation force. The	these nuclei settle, they tug on actin filaments, which in
result is that the plant bends in the opposite direction.	turn tug on the cell walls at their points of attachment.
Bending towards the light affords more efficient light	This tension triggers cellular changes in response to
capture by the upper leaf surfaces.	gravity, and on the side of the cell feeling gravity’s force,
Fungal gravitropism works in a similar fashion, but	microvesicles begin to fill and expand, vacuoles expand,
was poorly understood until recently. Careful grafting	and the entire process causes the expansion of hyphal
experiments were carried out using maturing	cells. The net result is that the stem of the mushroom
Flammulinabasidiocarps to test the effects of	you collected earlier in the day continues to bend away
gravitropism. Flammulinawas chosen for their long	from the gravitational sensation—even hours after you
stems and ease of cultivation (these are enoki	picked it.
mushrooms common in Asian markets). The part of the	Gravity, as well as temperature and moisture, are
mushroom most sensitive to gravity’s effects is the apex	abiotic factors that affect mushroom formation. Believe
of the stem. This was discovered with careful	it or not, light also may be required. While most would
manipulation of the mushroom caps and stems. As	suspect that fungi have no need whatsoever for light,
fruitbodies began to develop, the mushroom caps were	there are in fact many fungi that show a phototropic
removed and replaced (grafted) with either caps, or caps	response. Growers of Shiitake mushrooms (Lentinula
with stem apices (and sometimes inverted stems). The	edodes) know that this species will not form mushrooms
effects of the various grafts demonstrated “acropetal	at all in the absence of light. The common stalked
transport” of mycelial metabolites through living	polypore Polyporus brumaliswill grow towards light.
hyphae of the stem which induced the bending of the	Many other mushrooms will fail to form caps or
mushroom stems in response to gravity.	produce malformed fruitbodies in the absence of light.
Those metabolites seem to serve as a signal of	This is likely an evolved failsafe. Thus, if the hyphae are
gravitational forces, though it’s not entirely certain how.	unable to emerge from under the bark of rotting wood,
It is likely that gravitational sensing in fungi is similar	or from other debris or substrate, the fungus won’t
to the system of otolith organs of humans deep inside	waste any effort making a fruitbody that won’t
our inner ears. We keep our balance and know which	effectively launch spores.

way is up and down because of organs of the inner ear that contain a liquid filled with tiny stone-like particles called otoliths or otoconia (they really are stony, essentially made of limestone and a protein) that rub

SPORE DISPERSAL

Fungal tropism

A mushroom stem bends in response to gravity with the result that the cap becomes horizontal and mushroom spores are released, falling straight down, free from the gills beneath the cap.

By bending in response to gravity, the mushroom gills are now vertical as opposed to horizontal, thus ensuring the effective release of spores.

If the mushroom stem remains horizontal to the ground the spores cannot be released from the gills with much success, as can be seen here in the close-up.

REPRODUCTION

 Winter Polypore (Polyporus brumalis) emerging from woody substrate.

 Fruiting of cultivated Shiitake mushrooms (Lentinula edodes).

SPORE DISPERSAL

REPRODUCTION

GASTEROIDS	Upside Down Puffballs are found in dry and
Not all basidiomycete fungi are ballistosporic. Gasteroid	exposed plains in Australia, Europe, and North America.
fungi, which include stinkhorns, puffballs, and bird’s	Grazing mammals frequent these habitats and it has
nest fungi, require wind or water (or a well-placed	been suggested that the puffballs benefit from being
kick) to release their spores. However, while most	kicked or trampled by the hooves of animals passing
puffballs puff out their spores through a hole in the top	through. Indeed, on every occasion that I have seen
of the fruitbody, the Upside Down Puffball (Disciseda	these weird mushrooms, they have always been growing
species) does things differently. This curious mushroom	right along the paths used by cattle or sheep.
forms upside down, so the heavier basal casing—complete	Cute little bird’s nest fungi are a gasteroid form that
with soil and debris stuck to it—is initially at the top,	is found all over the world. They produce their spores
while the ostiole or spore exit hole is at the bottom.	in small packets (peridioles) that appear as “eggs” in a
The reason this oddity works is because the puffball	nest-like cup. A raindrop hitting the cup will splash the
is partially buried and loosely attached to the	eggs several inches or even a few feet distant, where
surrounding soil as it develops. As the puffball matures	they will stick to leaves or attach to twigs. Many are
it dries and shrinks, and becomes looser in its mooring.	specialized to decompose dead twigs and branches of
It is eventually dislodged by wind or rain, releasing	the forest canopy high overhead, although you might
spores as it rolls away. As its base is heaviest the	wonder how they stay up there—surely the rain would
mushroom comes to rest bottom-side-up, revealing the	splash and wash all the peridioles down to the floor
ostiole exit hole.	below? The secret is that many of these species have

Splash cup spore release

Bird’s nest fungi are decomposers that produce spores in egg-like packets (A) that splash from cups. Upon ejection, a tiny anchor trails behind (B), that snags on plant matter nearby (C). The fungal spores germinate and begin life for the next generation (D).

D B

evolved a very fine cord of hyphae known as a	is the actual technical term for the lush grass that goes
funiculus, which is attached to their peridiole spore	ungrazed in the immediate vicinity of cow poop.
packets. When the peridiole is splashed from its cup, the	The solution is that many coprophilous fungi
funiculus trails behind like a tiny anchor and sticks to	discharge their reproductive propagules toward the
the first twig it touches, wrapping the peridiole tightly	light, firing them far enough to escape the zone of
around it.	repugnance—Pilobolusspecies can fire their propagules
There are many other fungi species that release	an amazing 8 feet (2.5m) horizontally. In each case,
all of their spores within a single tidy packet. Some	discharge occurs during the day, with a black melanized
coprophilous fungi produce spores within resistant	peridiole case protecting the spores inside from the
packets that can actually pass through grazing animals	injurious effect of light.

and emerge from the other end, along with their substrate (manure). But how does a fungus growing in dung get its spores into another ruminant? When it

comes to grazing animals like cattle, this is no easy

سLooking every bit like eggs in an

actual bird’s nest, tiny fungal peridioles

trick, as cattle are notorious for avoiding one another’s

of Crucibulum laeveawait a well

feces—pastures contain a “zones of repugnance,” which

placed raindrop to be ejected.

REPRODUCTION

Zoochory

Wind is one of the major modes of fungal spore dispersal, but animal-mediated dispersal (zoochory) also plays a key role. However, much less is known about zoochory, as only about 1 percent of the tens of thousands of known species of fungi has an association with animals. In time, though, our knowledge of animal-associated fungi is sure to improve, and may reveal that some of these associations are underpinning entire ecosystems.

ZOOCHORY

For sequestrate fungi that produce hypogeous (underground) sporocarps, such as truffles, there almost always has to be an animal vector to assist with spore dispersal, and mycophagy—the consumption of fungi by

شThe fungus beetle Scaphidium	various organisms—is also likely to be an important mode
quadrimaculatumfeeds on hyphae	of dispersal for arbuscular mycorrhizas in plant roots.

and mushrooms, and undoubtedly

We know that hypogeous truffle and truffle-like

transports fungal spores to new

substrates.

fungi are consumed by many different mammalian

, including rodents, deer, wild pigs, and primates, while turtles are known to consume both epigeous (on the ground) and hypogeous mushrooms. In Australia, hypogeous truffle and truffle-like fungi make up a large portion of all macrofungi, and small mammals are undoubtedly crucial to the diversity of fungi there, while in New Zealand—where birds dominate the food webs—sequestrate fungi produce fruitbodies that resemble berries lying on the forest floor. In many cases, mammals have been shown to not only disseminate viable spores after ingestion, but in some cases actually increase spore viability through digestion.

The process of ingestion and subsequent defecation is known as “endozoochory,” but fungal spores can also be transported on the exteriors of animal vectors, which is known as “ectozoochory.” Insects can, of course, bump against molds and fruitbodies and haphazardly carry away some spores, and yeast fungi can travel from fruit to rotting fruit or flower to flower on the mouthparts of insects or birds. But many fungi have evolved elaborate strategies to deliberately entice animal vectors.

REPRODUCTION

Among the best known are the Phallales (stinkhorn)	All sizeable mushrooms are attractive to mycophagous
mushrooms, which produce putrid odors that attract	(mushroom-feeding) flies and other arthropods, and if
scavenging flies. The (reportedly) sweet-tasting gleba	you forage for wild mushrooms you will have seen (and
spore masses are lapped up and stick to the flies, which	probably eaten!) their larvae. It may seem curious that
then transport the spores to other suitable substrates,	fungi have not evolved arsenals of anti-feedant toxins in
such as manure or rotting vegetation. There is evidence	the same way as plants, but there is evidence that fungi
that viable spores can also pass through the digestive	may actually benefit from arthropods consuming
tracts of these fly species.	mushroom tissue and spores, and that this aids in their

dispersal. This is something that has been shown among resupinate fungi that produce fruitbodies in out-of-the

way surfaces like the undersides of fallen logs. This

سTomentella radiosais a resupinate

lifestyle seems at odds with the typical fruitbody forms

fungus that grows and sporulates on

the underside of fallen logs.

that are upright and in the air column, but fruiting

close to the soil has its advantages: this is where slugs,

Spores of Tomentellasp. ض

collembolans, and other arthropods are grazing. For

زA freshly emerged stinkhorn

resupinate fungi such as the ectomycorrhizal Tomentella

mushroom like this Phallus impudicus

will be covered with a goopy muddy

sublilacina, these soil food webs are the perfect way to

looking mass of spores that will quickly

get spores dispersed.

be gobbled up by flies.

REPRODUCTION

INSECT SYMBIONTS	The ambrosia fungi are perfectly adapted to
There are many instances where groups of insects are	symbiosis with the beetles and occur in two forms.
obligately associated with fungi. In some cases the	The first is a filamentous hyphae that grows within
fungus is a food source, and certain insect species have	beetle galleries, producing a dense layer of easily grazed
evolved pouches (mycangia) on their bodies to ensure	conidiophores (“ambrosia”) for the beetles to feed on.
that the fungus goes wherever they go. In the case of	The second is a yeast-like morphology that is cultivated
xylophagous (wood-boring) insects, fungi are needed	and nourished inside the mycangium by glandular
to break down the wood that they eat—without fungi	secretions of the beetle.
(or their enzymes) the insects cannot digest woody	As these fungi species live trapped deep inside beetle
cellulose. Some of these insects inoculate the wood,	tunnels, it is thought that mycangial transport is the sole
and after a period of time will begin feeding on the	means of transmission, although the most primitive ambrosia
now-digestible wood, while other fungal symbionts	beetles have no real mycangium (in this instance it is thought
are plant pathogens that attack and weaken the host	that spores of ambrosia fungi may be carried in the beetle’s
tree, making it more prone to beetle attack.	digestive system instead). Slightly more advanced species
The most fascinating of xylophagous insects are the	have nonglandular mycangia (simple depressions) on the
ambrosia beetles, which are one of the most diverse and	surface of their exoskeletons, while the most evolutionary
widespread groups of fungus-farming insects known.	advanced clades of ambrosia beetles have, independently,
These insects bore through wood and inoculate it with	evolved specialized pouch- or pit-like glandular mycangia.
ambrosia fungi, before spending their lives feeding	It should be noted that mycangia have evolved several times
exclusively on the fungal gardens growing on the	within the coleopterans, as well as other arthropods;
walls of their sapwood galleries and tunnels.	mycangial wood wasps feature later in this book.

Beetle nursery

Ambrosia fungus grows in the hollowed out chambers of Ambrosia beetles, Xlosandrus crassiusculus. The larval grubs feed exclusively on the fungus, grazing it from the tunnels inside the tree host.

زBark beetle (family Scolytidae) larvae tunnel through and consume wood that has been partially broken down by the action of wood rot fungi.

REPRODUCTION

Mimicry

Some fungi have evolved amazing tricks to coerce animals into transmitting their spores, including mimicking flowering plants, complete with “pseudoflowers.” Through natural selection, these fungal tricksters best the plants at their own game—think of this as legerdemain in the fungal domain.

Mimicry is the adaptive resemblance of one organism	During the reproduction cycle, the fungus forms
to another. The best-known examples of mimicry	a sterile mass of hyphae (termed a stroma; plural is
come from animals that exploit one another to gain	stromata) on the exterior grass stem surface. The stroma
protection from predators, such as the monarch and	hyphae are of a single gender, or mating type, and
viceroy butterflies, but there are equally fascinating	produce simple unfertilized spores called spermatia.
examples of mimicry among plants and fungi, many	Spermatia function in much the same way as the
of which still await discovery.	haploid pollen of plants: they waft by air or are carried
The fungus Epichloë elymi(formerly E. typhina)	by pollinators to another individual of the same species,
is an ascomycete pathogen of grass plants, and a	completing fertilization.
member of the Clavicipitaceae; this family includes	It was recently discovered that flies of the genus
many grass pathogens, including the historically	Botanophilaserve as the “pollinator” for Epichloë. Female
infamous Claviceps purpurea(see page 88), which is the	flies are attracted to (and consume) the fungal stromal
cause of St. Anthony’s fire. Epichloëlives entirely within	tissue and oviposit a single egg on the stroma. The adult
the host plant—such fungi are known as endophytes.	flies visit stromata on other grass plants and are known

to defecate viable spermatia. The result from this “pseudopollination” is that the fungus completes sexual reproduction and produces ascospores. The mutualism is thought to be an obligate one for both species; the fungal spermatia are not thought to be dispersed by wind or water, and Botanophilaspecies are thought to feed exclusively on Epichloë.

رBotanophila fugaxfly adult.

زA common endophytic fungus, Epichloë elymi, lives entirely inside Elymus virginicusand produces a cottony white stromata on the surface of its grass host during reproduction.

MIMICRY

SCOURGE OF ERGOTISM

In the Middle Ages, a frightening disease of humans known as “holy fire” or “St. Anthony’s fire” was common, albeit unpredictable. Symptoms included a tingling or burning sensation of the skin, paralysis, convulsions, tremors, and hallucinations; women frequently miscarried and fertility was generally reduced during outbreaks. The cause was ergot poisoning (ergotism), which causes blood vessels to constrict and blood pressure to rise. Some victims develop gangrene of the extremities (many victims lose their hands and feet) and thousands have died—in some documented epidemics in the 1800s the mortality rate averaged 40 percent. Although ergotism is now rare, outbreaks still happen occasionally, with the largest outbreak in modern times affecting an entire village in France in 1951.

REPRODUCTION

MIMICRY

There is very little wind at ground level in dense	the fungi’s conidia to healthy flowers, spreading the
tropical forests, so the flowering plants that live there	plant pathogen. The fungus overwinters on the soil as
also have to rely on insect pollinators rather than wind	sclerotia, which are masses of fungal tissue within
pollination. It’s likely that many fungi have similar	withered “mummified” fruits (hence the disease name:
strategies, as suggested by a strange symbiosis involving	mummyberry). The disease cycle begins again in the
a tree, a fungus, and a gall midge fly in the tropical	spring when the sclerotia produce small fruitbodies
forests of Borneo. The tree in question is a monecious	that release infectious spores to newly emerging
species of Artocarpus, which means it has both male and	leaves—the leaves that will become the pseudoflowers
female flowers. Known locally as “chempedak,”	for this floral mimic.
scientists have discovered that a zygomycete fungus,	While there are examples of fungi mimicking
Choanephora, can infect male flowers of the tree. This	plants, there are very few examples known where plants
fungus is consumed by the adults and larvae of a gall	turn the tables and mimic fungi. Although this book is
midge (Contariniaspp.) that feeds on the flowers, and	about fungi, it is worth featuring one plant that is so
these unwitting flies then not only transmit the pollen	good at mimicking a fungus that it’s unlikely many
from the male flowers to female flowers of Artocarpus,	people could tell the difference! Within the cloud
but also the fungal spores. In this way, having an animal	forests of the Central and South American tropic
pollinator not only benefits the chempedak tree, but	region is an orchid known as Dracula. In total, there are
also the fungal pathogen.	more than 100 species of Dracula orchid, which inhabit
The leaves and floral shoots of blueberry and	the sodden drippy ledges where few other flowering
huckleberry plants frequently become parasitized by	plants dare tread. As a result, there are few pollinators to
the discomycete fungus, Monilinia vaccinii-corymbosi.	be found, but there are plenty of mushrooms fruiting
When this happens, the infected tissues become	year round from the moist humus. So, like the result of
discolored and hyphae emerge epiphytically to produce	some evolutionary tantrum, Dracula species have cast in
conidia. Infected tissues seem to reflect ultraviolet light	their lot with mushroom-feeding flies to satisfy the
of wavelengths similar to those of the plant’s own	need for pollination. The Dracula orchid’s showy floral
flowers, and the fungal hyphae seem to produce sweet	parts closely resemble gilled mushrooms, complete with
secretions, along with infectious conidia. These two	mushroom smell. That’s right, the orchids produce the
elements—color and nectar-like exudates—appear to	exact same odor as mushrooms, a chemical called
attract the normal plant pollinators, which then transfer	“1-octen-3-ol,” to complete the charade.

رDracula chestertonii is a species of orchid endemic to Colombia. The name Dracula literally means “little dragon” and was applied to the genus because of the blood-red-colored flowers and long sinister-looking sepal spurs. This species of Dracula orchid was named in honor of Henry Chesterton who discovered the species. Joseph Henry Chesterton (1837-1883) was a famous British plant collector employed by James Veitch & Sons to search for rare and unknown orchid species in South America, with much success. It was on his final trip that he discovered this amazing species but its ecology has remained a secret until recently.

REPRODUCTION

PUCCINIA MONOICA

Phoenicaulis Rust

	SCIENTIFIC NAME	Puccinia monoica
Flower mimic	PHYLUM	Basidiomycota
	ORDER	Pucciniales
	FAMILY	Pucciniaceae
	HABITAT	Alpine

The most extreme example of floral mimicry is	spermatia are vectored to receptive hyphae on other
demonstrated by the rust fungus Puccinia monoica,	plants’ pseudoflowers, facilitating sexual reproduction
which is a pathogen of mustards in the genera Arabis	(“pseudopollination”) in the fungus.
and Phoenicaulis(family Brassicaceae). Barbara Roy,	Curiously, it appears that the fungal imposters may
an Oregon scientist who studies ecological associations	be beating the plants at their own game, as infected plants
of fungi and plants in North America and Europe,	“bloom” earlier than uninfected individuals, and yellow is
discovered that following infection the fungus inhibits	the dominant color of flowers in many ecosystems, including
floral production by its host plant and induces the	the montane habitat of Phoenicaulis. This fungus may also have
production of elevated pseudoflowers that bear no	a detrimental effect on the reproductive success of many
resemblance to its host’s flowers.	other plant species in the environment, as the odor and
	sweet rewards of infected plants may be more enticing to
A common host for Puccinia monoicais Phoenicaulis	pollinating species of insects than those produced by
cheiranthoides. Uninfected plants are short and squat, which	other floral species.

is typical of plants inhabiting arid, high elevations, and they bloom with small pink flowers. Infected plants, however, produce a greater number of leaf rosettes, no true flowers, and bright yellow pseudoflowers.

A second host of Puccinia monoicais Arabis hoelboellii, which is a tall, erect plant with thin strap-like leaves that are similar in appearance to blades of grass. Arabis hoelboelliiusually blooms with tiny white cruciform flowers, but upon infection the plants remain short and produce yellow pseudoflowers.

In both associations, the infected host plants produce pseudoflowers that are a different color from the uninfected form. A close inspection reveals that these pseudoflowers are actually a rosette of petal-like leaves that are covered by fungal spermogonia—the source of the bright yellow color.

 Rockcress, Arabis hoelboellii,

Likewise, the fungal hyphal tissue emits a fragrant odor and a

showing pseudoflower rosettes

sweet, sticky substance that contains spermatia. These

of leaves.

REPRODUCTION

PHALLUS INDUSIATUS

Bamboo

	SCIENTIFIC NAME	Phallus indusiatus
	PHYLUM	Basidiomycota
	ORDER	Phallales
Stinkhorn
	FAMILY	Phallaceae
	HABITAT	Forest and urban
Odor attractants

At first glance, the early stage of this fungus might	or “claws,” or appearing as a “cage”). Many have common
appear to be a clutch of bird’s eggs partially buried	names that are often evocative, including Stinky Squid
in organic debris, or possibly some unusual puffballs.	(Pseudocolus fusiformis), Anemone Stinkhorn (Aseroë rubra),
But return to inspect them a day or two later and	Lizard’s Claw (Lysurus cruciatus), and the Impudent Stinkhorn
the “eggs” will have split open and an obscene,	(Phallus impudicus), to name but a few. The beautifully veiled
foul-smelling fruitbody popped out.	Bamboo Stinkhorn (Phallus indusiatus) is a popular cultivated
	mushroom in Asia.
Stinkhorns are known from all continents except	Somewhere along their evolutionary history, members
Antarctica and many are very common urban mushrooms,	of the Phallales lost the ballistosporic habit, enticing insects—
living saprobically in organic debris. Indeed, some species	especially scavenging and carrion-feeding flies—to transmit
are cosmopolitan, having been introduced through the	their spores instead. As the fruitbody matures, a stinking gleba
importation of wood mulch and horticultural plants.	mass is produced, which contains basidiospores. Its foul odor
It’s unpredictable when they will turn up, but wherever	attracts flies, which feed on the gleba, typically removing
they are spotted, they always get attention. Some resemble	the entire spore mass within the space of a few hours.
undersea life, like squids or polyps, but many run the gamut	The ingested basidiospores pass through the flies and
from puritanical (complete with a golden or pure white veil)	are defecated elsewhere.

the prurient (unabashedly resembling sex organs). Charles Darwin’s eldest adult daughter Henrietta (“Etty”) took especial delight in destroying them whenever she encountered them in the woods near Down House, lest the virtues of the servants be sullied.

Given their appearance, it’s little wonder that mycologists erected a special order for them: the Phallales. Most stinkhorns can be classified into two main groups within the order, those that are unbranched (and typically

phallic-shaped), and those that are branched (having “arms”

 Phallus indusiatus.

REPRODUCTION

SPHAEROBOLUS STELLATUS

Artillery Fungus

	SCIENTIFIC NAME	Sphaerobolus stellatus
Explosive spore release	PHYLUM	Basidiomycota
	ORDER	Geastrales
	FAMILY	Geastraceae
	HABITAT	Forest and urban

A number of fungi benefit from human practices such	more like catapults, with the launch powered by the explosive
as transportation, agriculture, and even landscaping.	eversion of a pressurized membrane within the sporophore.
Many fungi are well suited to life decomposing the	Peridioles are shot toward bright light and can travel up to
ubiquitous wood mulch that is so popular these days in	feet (6m), with the force of the spore ejection producing
the urban landscape. In fact, there is so much demand	an audible sound.
for wood mulch that it is created and shipped all over	In recent years, Artillery Fungi have become a source
the world, with the unintentional introduction of many	of distress to homeowners, landscape mulch producers, and
fungal species into exotic habitats.	insurance companies, as the strong adhesion of the discharged
	peridioles sticks irreversibly to any smooth surface—the
Members of the genus Sphaerobolusare rarely noticed	pint-sized popguns have been known to mar the surfaces
growing on wood chips and mulch. These tiny fungi are	of vinyl sidings on homes, windows, and automobiles.
known as Artillery, Cannon, and Shotgun Fungi for their	So be wary of parking near mulched “islands” in parking lots:
amazing ability to blast a spore packet (called a peridiole)	the entire side of your car can become peppered on one side
over a great distance. Technically, though, the cannons are	in as little time as it takes to pop in to the dentist’s office!

Pint-sized Popguns

The sequence of events for launch of spores by the Artillery Fungus. As the spore packet matures, pressure builds in the fruitbody that propels the peridioles great distances.

 Sphaerobolus stellatusgrowing in woody debris. Large white peridioles are ready to fire; empty fruitbodies are also visible.

REPRODUCTION

PSATHYRELLA AQUATICA

Aquatic

	SCIENTIFIC NAME	Psathyrella aquatica
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Mushroom
	FAMILY	Psathyrellaceae
	HABITAT	Aquatic
Underwater ballistospory

In 2005, Oregon’s Rogue River was the setting for an	mushrooms, and found spores of Psathyrella aquaticain the
unusual discovery: mushrooms were found there,	guts of caddisfly, mayfly, and black flies. This suggests that
underwater. Naturally, it was presumed that the	aquatic insects are involved in spore dispersal, either as
mushrooms were fruiting from woody debris that had	mycophagists, grazers, or filter feeders collecting spores as
fallen into the water, but this was not the case. Not only	they move along the mushrooms underwater. More data will
were the mushrooms new to science, but they have	be needed to confirm the roles of these invertebrates, but
been seen every year since their initial discovery was	aquatic insects certainly have the ability to counter the flow
made, and—most amazingly—they fruit underwater.	of water and move spores upstream, especially if they are also

being consumed by fish or birds that could move the spores

While several ascomycetes are known to grow and fruit

even further.

underwater, no aquatic gilled mushrooms had previously been known. The basidiomycete Gloiocephala aquatic—a tiny Marasmius-like species from eutrophic ponds in Patagonian Argentina comes close, but has no gills.

Psathyrella aquaticalooks similar to most other species of the genus that you would expect to find in the woods or compost piles near your home, and how it produces spores is still not known. Ballistospory is not supposed to work underwater, so one theory is that this mushroom must somehow create air bubbles on the gill surfaces and fire spores into them—rafts of spores have certainly been documented floating in the vicinity of fruitbodies. Alternatively, spores might also be spread as the mushrooms wither and float away.

Even when that question is answered, another remains:

how are spores transmitted upstream? In an attempt to explain

 Ballistospory is not supposed

how the spores might counter the constant flow of water,

to work underwater but somehow

the bizarre Psathyrella aquatica has

Oregon-based mycologist Jonathan Frank caught and

figured a way. Scientists are still

dissected invertebrates associated with the underwater

unsure how it does it.

REPRODUCTION

PAUROCOTYLIS PILA

Scarlet Berry

	SCIENTIFIC NAME	Paurocotylis pila
	PHYLUM	Ascomycota
	ORDER	Pezizales
Truffle
	FAMILY	Pyronemataceae
	HABITAT	Forest
Fruit mimic

Paurocotylis pilais a strange fungus that relies on	Possibly the most convincing berry truffle is Paurocotylis pila.
zoochory and mimicry during reproduction. In	Ascocarps begin forming just under the soil surface during
Oceania, the truffle-form is a much more common	late summer, and as the truffle matures it expands and becomes
fruitbody morphology than anywhere else, and digging	exposed at the surface, resembling fallen red fruit. The size
mammals are the most important vector of spores for	and color make it appear almost identical to the fruits of
the truffle-producing fungi of Australia. Truffles that	Podocarpustrees that mature and drop at the same time.
rely on mammals are mostly dull colored, but produce	The ecology of the Paurocotylis is not well understood.
very strong odors, as mammals most often forage by	The few known species of North and South America are
sense of smell. However, in New Zealand, birds are the	considered rare or endangered, and are hardly known.
dominant herbivores, and the truffle fungi there have	Paurocotylis pilais now found in the United Kingdom, where
evolved different tricks to entice them. Several species	it is thought to have arrived in the early 1970s from New
of sequestrate fungi produce brightly colored purple,	Zealand (its introduction has been linked anecdotally to
blue, or red fruitbodies that resemble berries lying on	a visit by a New Zealand rowing team). The genus was
the forest floor—foraging birds gulp these down and	originally presumed mycorrhizal, but recent studies suggest
deposit their spores elsewhere.	that members of this genus (and the related genera Geopyxis,

Hydnocystis, and Densocarpa) may be endophytic or saprobic, or both during their lifetime.

Truffle-like fruitbody

Fruitbodies of this fungus appear to be brightly colored berries but a cross-section reveals chambers lined with spore-producing hymenia.

 Scarlet Berry Truffles are actually pea-sized but shown here greatly magnified.

REPRODUCTION

PILOBOLUS CRYSTALLINUS

Hat Thrower

	SCIENTIFIC NAME	Pilobolus crystallinus
Explosive reproduction	PHYLUM	Zygomycota
	ORDER	Mucorales
	FAMILY	Pilobolaceae
	HABITAT	Forest and farmland

The dung of grazing mammals is a prime habitat for	DRAWN TO THE LIGHT
many fungi known collectively as “coprophilous.”	So how do they do it? Well, to start with, Pilobolus crystallinus
Likewise, the dung of grazing mammals is an excellent	is phototropic. It produces tiny stalked fruitbodies
place to view a microcosm of many different fungi that	(sporangiophores) that support a single apical sporangium
will come and go in quick succession. Pilobolus	spore packet and grow toward light. The end of the
crystallinus, known as the Hat Thrower, is often the first	sporangiophore is a bulbous vesicle that fills with liquid,
to colonize and the first to sporulate—usually within	causing it to swell in size. This “squirt gun” then acts as a lens;
just a few days.	light shines through the outer wall and is focused on the
	interior wall, opposite. A photoreceptor transmits a stimulus
When fresh, the rich cellulosic substrate—poop—is already	down the stalk below the vesicle, which reacts by growing
broken down mechanically, moistened, and at the perfect	more quickly on the side opposite the light source. The result
temperature, so it is colonized quickly by fungi. Its nutrition	is the sporangiophore bends to take aim in the direction of
is used up just as quickly, so Pilobolus crystallinushas evolved	the light. When the vesicle bursts, it hurls the black
a fascinating trick to ensure it is the first to colonize: it makes	sporangium toward the light.

sure its spores are already inside the dung when it leaves the animal. To achieve that goal, this fascinating fungus launches its spores in melanized packets called sporangia, making sure that it squirts them well outside the “zone of repugnance”—

the lush ungrazed grass in the near-vicinity of dung—where

Sporangium

they wait to be consumed by grazing animals.

Sporangiophore vesicle

Form follows function

Sporangiophore stalk

A single sporangiophore is bulbous-shaped	Sporangiophores of the Hat Thrower
and acts as a lens to focus sunlight, causing	(Pilobolus crystallinus) glisten with droplets
the sporangiophore to throw its “hat” into a	of moisture in this macrophotograph.
clearing. The black sporangium is a packet	Although the stalk is only a few millimeters
of spores, built to withstand the digestive	in length, the black sporangia can be shot
enzymes of herbivorous mammals.	m away from the substrate.

CHEMISTRY &PHYSIOLOGY

CHEMISTRY & PHYSIOLOGY

A strange chemistry

Among the kingdoms of life, the closest relatives to animals are fungi. This might not be apparent immediately, as fungi and animals look nothing alike morphologically, or indeed at a cellular level, but chemically and physiologically speaking we share many similarities, as well as a common ancestor.

A STRANGE CHEMISTRY

Unlike animals, fungal cells have cell walls, but inside the cell the chemistry is pretty similar: there are ribosomes, mitochondria, and DNA that is organized as chromosomes. Like animals, fungi do their digestion

ش The Velvet Foot mushroom

outside the body of the organism. Fungi digest organic

(Flammulinaspp.) are very commonly

seen rotters of wood.

matter by excreting enzymes into their substrate and

the digested material; similarly, animals gobble up food and store it in a vessel (stomach), into which enzymes are excreted and the digested material is absorbed across the epithelial lining that separates outside from inside the tissues of the animal.

Given the right conditions fungi can utilize just about anything as a food source. They can consume the pages of books, photographs, photographic film, and the coatings on camera lenses; they can digest disposable diapers, plastics, and other petroleum products (including crude petroleum from accidental oil spills); they have been found clogging the fuel lines of aircraft, have rotted the hulls of sailing ships for centuries, and can destroy just about any material in and around your home.

It is not just their feeding habits that are unusual. For instance, some fungi can glow in the dark; others produce some of the most toxic substances known in nature; and many can live in the absence of oxygen, sometimes producing copious amounts of alcohols as a result. Meanwhile, there are fungal pathogens of plants that can alter their host’s chemistry to create structures that resemble flowers or fruits, and fungal pathogens of animals that can take over their host’s mind and turn them into “zombies”—purely for the purpose of fungal reproduction.

MELANINS	and oxidizing chemicals, protect against lytic enzymes
Another chemical process that is shared between	or other toxins of microbes, and are the basis of
animals and fungi is the production of melanins.	virulence in some plant pathogenic fungi.
Melanins are one of the most widespread organic	Fungal melanins are mostly brown to black and
substances of life across all kingdoms; they are common	thus absorb visible and ultraviolet light, and to a certain
in many taxa and appear to play a key physiological role	extent infrared. This is particularly beneficial to fungi
in organisms. They may even be connected to the	that produce rhizomorphs (similar to plant roots) that
origin of life.	span from one substrate to the next, as they have to deal
These dark pigments are produced by animals to	with the physical stresses of sunlight and desiccation.
protect against ultraviolet radiation and other damaging	For example, rhizomorphs enable honey mushrooms
factors in the environment, such as the tan pigmentation	(Armillaria) to move from one tree stump to another,
in human skin in response to exposure to the sun. In	or to living trees, enabling their success as a forest
fungi, melanins play many roles, from the structural	pathogen. As a demonstration of how tough these
reinforcement of cell walls to affording protection from	rhizomorphs are, you will find them persisting on
thermal stress and desiccation, salt and pH stress, and	rotting logs long after the fungus—and much of the
radiation (ultraviolet light, ionizing radiation, and so	wood—is gone.

on). Melanins also act to “soak up” toxic heavy metals

A STRANGE CHEMISTRY

ر The very common Honey

formidable human pathogens such as Cryptococcus

Mushroom (Armillariasp.) is a serious

pathogen of forest trees, and continues

species are melanized; melanin-deficient mutants lose

to grow saprobically on the dead wood.

their ability to cause infection.

Melanins show high tensile strength and thus reinforce cell wall structures such as spore walls. In this

Heat and cold are additional stresses that can be	way, melanized fungal cell walls better resist osmotic
alleviated by melanins, as demonstrated by Monilinia	stress and turgor forces. Furthermore, melanized spores
fructicola, an ascomycete that causes brown rot of	are much more resistant to desiccation and hazardous
stone fruits. This species is able to grow at high	UV-radiation. Ionizing radiation (including UV light)
Mediterranean temperatures, whereas melanin-deficient	damages DNA and therefore can be destructive to all
mutants cannot. Indeed, many microfungi and lichens	living cells. Without melanin (or gobs of protective
are melanized, especially those that inhabit extreme	sunscreen lotion), our own skin cells are at risk from
substrates, such as rocks in cold environments.	sunlight; skin cancer is a result of DNA damage from
Melanins also serve as antioxidants and resist lysis	ionizing radiation. Fungi that produce hyaline or
(cell disintegration) by enzymes, as well as microbial	colorless spores typically are not viable for very long,
attacks. The latter properties seem to enable many plant	but some fungi, such as Ganoderma, produce darkly
pathogenic fungi to overcome host defenses and thus	pigmented, melanized spores that can remain viable
contribute to the virulence of the pathogen. Likewise,	for years in soil.

AUTOTROPHIC FUNGI

Remarkably, another form of radiation— atomic radiation—seems to cause enhanced growth in some melanized fungi, as demonstrated by samples of Cladosporiumand Penicilliumthat have been isolated from the Chernobyl reactor ruins. Amazingly, these fungi seem to harvest energy from ionizing radiation, making them autotrophic by a process that has yet to be understood. Here spores of Cladosporium can be seen under microscopy having been digitally-colored.

CHEMISTRY & PHYSIOLOGY

BEAUTIFUL DECAY

Fungal melanins can often be seen with beautiful results in spalted wood. You may have seen beautiful wooden objects, such as guitars, furniture, cabinetry, or small art objects like bowls, made of “curly maple” or “birds-eye maple.” There are no such trees, of course—this wood, with its beautiful patterns of dark blackened zones, is actually wood that has been invaded (and often times

distorted) by microbes including fungi. Fungi such as

ش Elaborately spalted wood results

from fungi and other microbes battling

Armillaria, Xylaria, and a few others, grow into the

over resources.

wood and surround their zone of infection by what are

ز Xylariaspecies (top photo) are

called “pseudosclerotial plates.” When the wood is cut	commonly seen wood rot fungi. These
	ascomycetes produce spores from tiny
and finished these plates appear as dark lines, but if you
	chambers buried within black stalks
could see the wood in three dimensions, you would see	called stromata.
a column of woody tissue surrounded by fungal hyphae	ط The wood rot fungus Physisporinus

vitreusis a basidiomycete polypore

and lots of melanin. In this way, the fungus almost walls

and produces spores from tubes,

off its zone from anything outside, including other fungi.

shown here (bottom photo).

A STRANGE CHEMISTRY

The polypore mushroom Fomes fomentarius demonstrates dark spalting beautifully, while other fungi that attack wood can leave behind different colored lines; Chlorociboriais a wood rot fungus that discolors wood a beautiful blue-green color. In the early stages of decay—before the integrity of the wood is compromised and weakened—such wood is highly prized by artisans.

If you’re a classical music buff, you will know there are lots of factors that go into the sound of a famed Stradivarius violin, from the type of wood that was used to the way it was aged, and no doubt the chemicals and glues used during production. Yet, despite centuries of research by scientists and musicians, much of what makes a Stradivarius special remains a mystery.

However, some researchers think they are getting closer. Recently, scientists produced a very inexpensive violin made of wood that had been treated with two types of wood rot fungi: Physisporinus vitreusand Xylaria longipes. The species of wood used were the same as those used by professional violin makers: Norway spruce for the instrument’s body and sycamore for the back, ribs, and neck. What is unusual about Physisporinus and Xylariais that they gradually degrade the cell walls of the wood they infect, thinning them rather than destroying them completely. In doing so they leave a stiff scaffold through which sound waves can readily pass, without compromising the wood’s elasticity.

After an incubation period, the wooden planks were treated with a gas that kills the fungi, and then given to master violin makers for conversion into instruments. Once the instruments had been made, a team of audiophiles took part in a blind trial, and the results were dramatic: the expert jury concluded that the sound of the inexpensive “mycowood” violin was indistinguishable from that of a Stradivarius made in 1711. Seeing how concert-quality violins are a necessity for any young performer’s career, but are so expensive that young players often have trouble affording them, the development of mycowood instruments could go a long way toward democratizing the violin world.

CHEMISTRY & PHYSIOLOGY

BIOLUMINESCENCE

Among the many intriguing varieties of fungi are those that glow; bioluminescent fungi. Bioluminescence has been known and documented since ancient times. Although Aristotle and Pliny the Elder mentioned this phenomenon, naturalists mostly neglected the subject until the observations of miners in the eighteenth century garnered attention.

We now know that the source of the glow is not plants, but fungi, and that there are four known lineages of bioluminescent basidiomycete fungi, containing around 80 different species. Mushrooms familiar to us that glow include Armillaria, Mycena, Omphalotus, and Panellus—if the light comes from hyphae in wood (often called “foxfire”) then it is most likely a species of Armillaria.

Bioluminescence is widespread in nature, and in addition to fungi there are animals, plants, and bacteria that can do it. Two things to keep in mind about

س ز Omphalotus nidiformisis a pretty

bioluminescence are that it is ongoing, even in the light

drab mushroom when seen in the light of

of day (although it is not visible), and it generates no

day (above), but after dark these

mushrooms really shine!

heat, so is very different to incandescence, which is a

ILLUMINATING FUNGI

In 1796, the German naturalist Alexander von Humboldt was one of the first to describe the luminescence of rhizomorphs in German coalmines. A bright luminescence of wooden panels and beams was reported, which was apparently so bright that pit lamps were unnecessary. High humidity and temperatures within the mineshaft seemed an important requirement for light emission, which was described as coming mainly from the hyphal tips of “plants” (termed Rhizomorphaspecies).

CHEMISTRY & PHYSIOLOGY

thermal glow. The light originates from a metabolic	suggestion has been studied, but it doesn’t seem to
reaction of the fungus where electrons are transferred	be the case in temperate biomes. However, for very
to an acceptor molecule (luciferin), which is cleaved by	dense tropical forests, where there is little air movement,
an enzyme (luciferase) in the presence of oxygen. This	recent evidence indicates that bioluminescence may
results in the formation of an electronically excited	be a mechanism for spore dispersal by flying insects.
state of the luciferin and a subsequent emission of light	An alternative theory is that bioluminescence is
with a maximum wavelength of approximately 525nm	simply a way for fungi to dissipate energy as a by-
during return to the ground state. This process is much	product of oxidative metabolism, as most organisms—
the same for all organisms that bioluminesce, although	ourselves included—give off heat as a by-product of
the luciferins and luciferases are not exactly the same.	this process. This chemical reaction may also be tied to
Many people ask what is the “purpose” of	the detoxification of peroxides that are formed during
bioluminescence, and if it is of some benefit to the	ligninolysis (the breaking down of wood). Many
organism. Numerous functions have been postulated,	bioluminescent fungi rot wood and leaf litter, including
most notably that it serves in the attraction of	the white rot fungi, Armillaria melleaand Panellus
invertebrates for the purposes of spore dispersal. This	stipticus; factors that induce or depress the lignolytic

A STRANGE CHEMISTRY

system of white rot fungi are also shown to induce or	advantageous within certain fungi—perhaps for spore
depress bioluminescence.	dispersal—and has been retained as evolutionary
Currently, though, the function of bioluminescence	“baggage” by some members, having no real selective
remains elusive and controversial. Within the genus	advantage or disadvantage. My guess is that the trait
Mycena, for example, there are at least 33 species known	must be of some benefit, as it’s retained in so many
to bioluminesce. However, many more Mycenaspecies	species of fungi—but your guess is as good as mine.

not, which begs the question: did bioluminescence evolve once, with the trait then lost many different times throughout history, or did it evolve at different and independent times within the genus?

Some researchers suggest there is no evolutionary benefit resulting from bioluminescence in fungi, as genera such as Mycenahave glowing and non-glowing

ش Mycena roseoflava is a beautiful

species that all seem to be equally successful in nature.

little bioluminescent mushroom of

In these cases it is likely that bioluminescence was

Australia and New Zealand.

CHEMISTRY & PHYSIOLOGY

Intoxicating fungi

Of all the aspects regarding fungal chemistry, probably the most studied are the toxic compounds that fungi produce. Entire books have been written on this subject, which is so wide that it would be pointless to even attempt to summarize it here. However, because of their ubiquity, you will see references to fungal toxins throughout this book and in just about every chapter.

Toxins are substances produced by living organisms that poison the living system of another organism, blocking or disrupting the regular function of biochemical pathways or other processes. Fungi produce a dizzying array of compounds that are toxic to other organisms, including humans. Some of these compounds are almost certainly created as a defense mechanism to protect the fungi from other microbes, such as the bitter alkaloids of ergot fungi, which serve as anti-feedants. Other fungal toxins are used to kill the cells of the host organisms that some fungi live on, and there are also compounds that just so happen to be toxic when they end up inside us; amatoxins found in species of cosmopolitan mushrooms, including some Amanitaspecies, are infamous for causing deaths every year, but it remains unknown why fungi produce these compounds.

However, many toxic substances can be employed to cure the body of diseases. The famous Swiss physician Paracelsus (who pioneered research into what is now considered toxicology), is famous for pointing out that the difference between medicine and poison, often is the dose.

ز Although not deadly, the Fly Agaric (Amanita muscaria) is a commonly encountered toxic mushroom.

CHEMISTRY & PHYSIOLOGY

YEAST	popular technique for producing alcoholic beverages,
The beginning of agriculture and the domestication	with more than 250 billion dollars of global sales.
of plants and animals are among the most decisive	Unlike most ales and wines, lagers require slow,
events in human history, because they triggered the	low temperature fermentations that are carried out by
rise of civilizations and the attendant demographic,	cryotolerant (“cold-tolerant”) Saccharomyces pastorianus
technological, and cultural developments. The	(formerly called S. carlsbergensis). Strangely, S. pastorianus
domestication of barley in the Fertile Crescent led	has never been isolated from the wild, and depends
to the emergence of the forebear of modern beer in	entirely on humans for its propagation. This is pretty
Sumeria, some 6,000 years ago. Beer and other	unusual if you consider that Earth is awash in beer and
alcoholic beverages may have played a pivotal role in	most of that passes through (so to speak) this fungus.
cementing human societies through the social act and	A recent global inventory of wild yeasts has
rituals of drinking, and by providing a source of	discovered the origins of S. pastorianus, though. It turns
nutrition, medicine, and uncontaminated water.	out that this yeast was created through the hybridization
In Europe, brewing gradually evolved during the	of a Saccharomyces cerevisiaeale yeast and another,
Middle Ages to produce ale-type beer. This process uses	previously unknown cryotolerant Saccharomycesspecies.
Saccharomyces cerevisiae(“brewer’s yeast”), which is the	This begs the question: what exactly are brewing yeasts
same species involved in producing wine and leavened	doing in nature?
bread. In the fifteenth century, lager brewing arose in	Many different yeasts are found occurring
Bavaria, and by the late nineteenth century it had	naturally in the sap flows that exude from wounds
gained broad acceptance. It has since become the most	and cracks commonly seen on trees. In the Northern

Hemisphere, Saccharomycesspecies are associated	cryotolerant yeast S. pastorianusis necessary for
with oak trees, while other wild yeasts are found in	resolving the taxonomy and systematics of this
the sap flows of Southern Beech (Nothofagusspecies)	important species complex, and for understanding the
trees in the colder temperate regions of the Southern	key events that led to the domestication of lager yeast.

Hemisphere. It was an inventory of the yeasts of woodlands containing populations of Southern Beech trees that turned up the mystery yeast species that co-forms S. pastorianus. The new species was designated Saccharomyces eubayanusbecause of its resemblance to S. bayanus(a complex hybrid of S. eubayanus, S. uvarum, and S. cerevisiae, found only in the brewing environment).

Populations of the newly discovered S. eubayanus

س The Antarctic Nothofagus forest is

exist in the chilly Nothofagusforests in Patagonia, way

chilly and remote. It makes up part of the

Los Glaciares National Park in Argentina

down at the southern tip of South America. This is

and is shown here with the Cerro Torre

mountain looming in the distance.

a long way from Bavaria and Bohemia, so it is not

known how the ancestors of modern brewing yeast

ر Louis Pasteur, the French chemist,

was a pioneer of microbiology and

found their way to Europe, although there have been

fermentation science.

centuries of trade between Europe and South

رر Baker’s yeast, Saccharomyces

America. Identifying the wild genetic stock of the

cerevisiae, seen under microscopy.

CHEMISTRY & PHYSIOLOGY

It is interesting to note that the mystery yeast was found on the trees alongside another fungus associated with Nothofagus: Cyttaria. The fruitbodies of Cyttaria resemble golf balls clinging to the bark of trees. These fruitbodies are not only edible, but noticeably sweet, as this fungus is one of the few in the world to produce sugar. Elio Schaechter, a world authority on microbes, wrote that Darwin noted the natives of Tierra del Fuego ate these mushrooms, “although, oddly, they bypassed fresh specimens in favor of older, wizened ones. Some years ago, I came up with a possible explanation. Uniquely among mushrooms, Cyttaria have a concentration of fermentable sugars … could it be that [the Yanage] favored the older specimens undergoing fermentation? These people were surprisingly hardy; they were very scantily dressed, yet living under very harsh climatic conditions. I posited that a little alcohol from fermented Cyttarias may have gone a long way toward good cheer.”

Support of this notion comes from the modern-day people who live in this region and call the fruitbodies that fall from Southern Beech llao-llao. As well as consuming them outright, the fruitbodies are collected and fermented into a beverage called chicha de llaollao—could this drink be the “mother of all beers?” Perhaps. Cyttariaspecies certainly harbor the coldtolerant lager yeast, and undoubtedly this is what ferments the indigenous beer of South America. We will discuss Cyttariafurther on page 122.

ز Ripened fruitbodies of Cyttaria

darwiniimore closely resemble plant fruits than mushrooms.

INTOXICATING FUNGI

CHEMISTRY & PHYSIOLOGY

Although brewing yeast is well known, it is not	as the fungus imparts wonderful flavors and aromas
the only fungus involved in the manufacture of	to these famous wines. Wine Cellar Mold also keeps
humankind’s most-loved drug (alcohol). Many fungi	cellars free of other foul and musty odors.
respond to innumerable volatilized chemicals in the air,	If there are no volatile carbon sources in the air,
and some fungi can subsist entirely on volatile carbon	the fungus may be able to scavenge nutrition from its
sources that they pull from the air. Possibly the strangest	substrate. However, modern wineries and distilleries
is Zasmidium cellare, which is known more commonly	that use stainless steel, intensive sanitation and
as Wine Cellar Mold. This was formerly considered a	cleanliness, and ventilation in their production and
Cladosporiumspecies, given its resemblance (a greenish-	aging rooms will not be suitable. Perhaps, because
brown fuzzy mold growing over surfaces), but the way	of changing production practices and modernization,
in which this curious mold grows sets it apart from all	this fungus could soon become an endangered species?

other fungi.

As its name suggests, Wine Cellar Mold is found in traditional wine cellars and distilleries around the

world. If undisturbed, it can hang from the ceilings in

ر Zasmidium cellarehas gone by

many names and has been known for

lush sheets of hyphae, surviving solely on the volatilized

centuries. In the 17th century English

naturalist James Sowerby illustrated

alcohol in the air. The alcohol evaporating from the

and described its habit of forming

barrels—known as the “angels’ share”—can be

amorphous fuzzy colonies of aerial

hyphae hanging from ceilings.

substantial (amounting to 2 percent of the volume for

س Although it looks creepy and gross,

brandy and whiskey). Having sheets of fungus hanging

the Wine Cellar Mold, Zasmidium

from the ceiling might sound filthy, but the mold has

cellare, hanging from walls and

ceilings has been a welcome resident

been a welcome inhabitant of wine cellars for centuries.

of cellars for centuries in Europe and

This is especially true where Tokay wines are produced,

is responsible for cleaning the stagnant

air of contaminating odors.

CHEMISTRY & PHYSIOLOGY

Chemical mind control

There are many fungal pathogens of animals, of course, and we will return to them later in this book. But a very bizarre group of pathogenic fungi, which are specialists of insects and other arthropods, bears special mention.

With more insects on the planet than all other groups	(entomopathic), as well as plants, and even of other
of animals it is no surprise that many fungi are	fungi. Among the Entomophthorales, all species from
specialized to kill them. Two groups of fungi are especially	the family Entomophthoraceae are entomopathic
noteworthy: the Entomophthorales (long considered	(indeed, their name translates as “insect destroyer”),
zygomycetes) and Hypocreales (ascomycetes). Many	while the Ophiocordycipitaceae and Clavicipitaceae
members of these groups are parasites of insects	families are entomopathic species within the Hypocreales.

ر A zombie fungus (Cordycepssp.) seen emerging from its insect victim in Danum Valley Conservation Area, Sabah, Borneo, Malaysia.

CHEMICAL MIND CONTROL

Summit disease

Once a zombie fungus infects an ant, the fate is sealed for the host. The pathogen begins to consume the insect but just before death, instructs the host

The zombie fungus metabolites

to climb as high as possible where the

controlling the ant's CNS instruct the

fungus will sporulate.

ant to climb up high to a leaf where

The fungal cells grow	the fungus will eventually sporulate
around the ant's brain
and hijack its central
nervous system (CNS)

The ant is exposed to the zombie	Within the ant's mandibular
fungus spores found on the ground	muscles, the fungal cell population

grows, disrupting the organelle numbers and amino acid balance

The final death grip during which the ant suffers lock-jaw as a result of mandibular muscle atrophy

Although hypocrealean and entomophthoralean	their colony. From this position they too can rain
fungi are quite different, they have some amazing	infectious spores down on unsuspecting victims below.
similarities that have arisen through convergent	Eryniopsis lampyridium, which infects Goldenrod
evolution. Both fungal groups infect an insect host,	Soldier Beetles (Chauliognathus pennsylvaniaand C.
grow as hyphae throughout the animal’s body, and—	marginatus), has an extra trick up its sleeve. After summiting
just before death—take control of the host’s brain,	a goldenrod stalk, the doomed beetle clamps down and
instructing it how and where to move. It’s worth	dies. However, 15-22 hours later, at dawn, the dead
emphasizing here that both groups evolved from a	host’s wings open in a mating pose, encouraging other
different ancestor, but have hit upon “zombification”	soldier beetles to attempt to mate. The unwitting
independently—to me that is amazing!	suitors are then exposed to infectious spores, which are
The effects of these fungi and the ways in which	by then covering the abdomen of the initial host.
they reproduce are often incredible. For example, ants	Another zombifying fungus, of sorts, is Massospora
that have been parasitized by the fungus Pandora formicae	cicadina. This very strange entomophthoralean fungus
move away from the colony and, in most instances, are	is one of 14 species of a small, specialized genus.
compelled to crawl up and latch on to the substrate in	Charles Horton Peck (1867-1915), was a New York
an act known as “summit disease.” A macabre death	State botanist, who made 36,000 collections of fungi,
follows, as fungal sporophores erupt through the host’s	mosses, ferns, and seed plants during his famed career.
exoskeleton and spores are launched. Ants parasitized	Though not trained in mycology, he named 2,700
with Ophiocordyceps unilateralisalso become weaponized	species of fungi, possibly the strangest of which was
by the fungus, positioning themselves on foliage	Massospora cicadina. You can find out more about this
directly above paths frequented by other members of	gruesome species on page 96.

CHEMISTRY & PHYSIOLOGY

LOPHODERMIUM PINASTRI

Needle Cast

	SCIENTIFIC NAME	Lophodermium pinastri
	PHYLUM	Ascomycota
	ORDER	Rhytismatales
Fungus
	FAMILY	Rhytismataceae
	HABITAT	Forest and urban
Chemical warfare

All trees regularly drop their leaves and needles as part	(0.8mm) long. The black ascocarps are slightly raised and
of a process called senescence. Reduced sunlight at the	aligned lengthwise on the needle. When mature, they have
end of the growing season, drastic temperature	a longitudinal slit through which spores will be released.
changes, and droughty conditions can trigger leaf drop.	Even more interesting, you may notice black zone lines
Senescence is also one way that a plant can expel	across needles separating the Lophodermiumascocarps. These
pathogens. Dropped leaves and needles are a great	black zone lines are produced when one mycelium of the
place to look for a dizzying array of interesting fungi,	fungus encounters another growing within the plant
but most are tiny and you may have to look closely.	tissues—the same process that can be seen on a larger scale

with spalting in wood, where fungi causes the wood to It’s unlikely that you’ve ever noticed Lophodermium pinastri; change color. this tiny ascomycete looks like nothing more than black splotches on the needles of two-, three-, and five-needle pines. Lophodermiumspecies are well known pathogens of both broadleaved trees and conifers worldwide, causing afflicted needles to drop from the latter. All species of the genus are thought to live saprobically on dead leaves and needles, while some species, such as Lophodermium pinastri, live asymptomatically as an endophyte inside the tree’s needles.

If you have pine trees growing nearby, it is worth going and having a look for this fungus. Fruitbodies of Lophodermiumoccur on dead needles remaining on the tree or those already on the ground. As noted, the fungus doesn’t look like much at first glance, but there is more to it than meets the eye. Upon examination, the pine needles will likely exhibit shiny black, football-shaped ascocarps, just 0.03 inches

 Tiny fruitbodies denote colonies

of Lophodermium pinastrigrowing within pine needles.

CHEMISTRY & PHYSIOLOGY

CLAVICEPS PURPUREA

Ergot

	SCIENTIFIC NAME	Claviceps purpurea
Historically toxic	PHYLUM	Ascomycota
	ORDER	Hypocreales
	FAMILY	Clavicipitaceae
	HABITAT	Grassland

There are more than 40 species of Clavicepsfungi,	a homeless beggar, a bedridden elderly woman, and Tituba,
all of which are parasites of grasses, rushes, and	a Caribbean slave girl. Only Tituba gave a forced confession:
sedges. The best known is Claviceps purpurea, which is	she had made a pact with Satan and she implicated several
found in all temperate regions and has a host range of	other co-conspirators. Hysteria swept through the village
more than 400 species, including important cereal	and the witchcraft trials ensued, lasting several weeks.
grains. The fungus infects only the ovary of its host and	Preposterous testimony was the only evidence presented;
this is the most recognized stage of its life cycle. An	those who confessed or named other witches were spared
infected ovary (kernel) becomes replaced by a hard,	execution, but those who argued their innocence were not
curved, purple-black sclerotium (or ergot).	so lucky. In the end, nineteen women were hanged and an

elderly man was crushed to death beneath heavy stones. In late spring, and timed to coincide with the flowering stage of the host plant, the sclerotia lying on the ground germinate to form tiny stalked stromata that resemble minute mushrooms.

 Purple-black ergot is a sign of

Embedded within the stroma are fruiting bodies that produce

infection with Claviceps purpurea

on cereal grains.

sexual spores (ascospores). These spores are forcibly discharged into the air and enter the host plant through the flower, much

Ergot sporulation

like pollen would.

When time for sexual reproduction, tiny

Although ergot reduces cereal crop yields by replacing mushroom-like growths emerge from a single sclerotium that was produced on the host plant

the host’s kernels with sclerotia, it is the toxic alkaloids

and overwinters on soil.

produced by the fungus that are of greater significance,

Stroma

as these mycotoxins are a health risk to humans and livestock

Sclerotium

or ergot

alike—their effect known as ergotism. Modern cleaning methods remove ergots from grain before it is milled or used for animal feed, but the process is costly and may still leave toxic residues. Long blamed on mass hysteria, it is likely that the infamous Salem Witch trials of Massachusetts were a result of ergotism. Beginning in February of 1692, some of the young girls of Salem fell into convulsive fits, screaming, and speaking in tongues. Upon interrogation, the girls blamed

CHEMISTRY & PHYSIOLOGY

FOMES FOMENTARIUS

Tinder Polypore

	SCIENTIFIC NAME	Fomes fomentarius
Fire starter	PHYLUM	Basidiomycota
	ORDER	Polyporales
	FAMILY	Polyporaceae
	HABITAT	Forest

Fomes fomentariusis considered a pathogen, as it is	(known as “German fuse”)—once ignited it would burn very
commonly found growing from the main stems of living	slowly, allowing it to be preserved and transported for hours
trees. More likely, though, the polypore—a white rot	and even days.
fungus—is a saprobe, restricted to the dead heartwood	In September 1991, hikers discovered the mummified
of the tree. The fungus continues to grow on wood long	body of a man emerging from a thawing glacier in the
after the host tree is dead, leading to beautiful spalting,	Tyrolean Mountains on the border between Italy and Austria.
as discussed earlier.	Dubbed ضtzi, the cadaver was thought initially to be that of
	a hiker who had become lost and fallen into a crevasse, but
Known as the tinder polypore (the specific epithet refers to	researchers at the Archaeological Museum of Alto Adige,
“tinder for fire”) this cosmopolitan fungus produces large	in Bolzano, Italy, discovered that the man had lived between
brackets that are commonly seen throughout the Northern	,300 and 3,100 BC. When he died, ضtzi was carrying a rich
Hemisphere. During excavations of prehistoric villages in	supply of artifacts, including a bow, arrows, and a piece of
Italy and Switzerland, the remains of F. fomentariusrevealed	Birch Polypore (Piptoporus betulinus) that would have been
that the brackets have long been used to kindle fires—this	used to stop bleeding. He also had a piece of Fomes
practice probably dates back as far as the Paleolithic era,	fomentarius, wrapped in green leaves and stored in a
,000 years ago.	container—no doubt the tinder polypore was smoldering
In seventeenth century Germany and France, a cottage	inside at the time of his death.

industry was based on the manufacture of fire-starting kits utilizing this fungus, with each kit including prepared tinder fungus, a striking steel, a shaped silica stone, all packaged in a small tin box or a little bag. The industry employed many people, from mushroom collectors to manufacturers who processed the mushrooms; by the early 1900s, one particular manufacturing plant in Ulm, Germany, was producing 50 tons of material per year and employed about 70 workers.

As it produces no flame, smoke, or foul odor, the pounded

 Fruitbodies of perennial polypores

mushroom tissue also proved very useful as a wick or fuse

like Fomes fomentariuspersist on trees

for many years, adding a new sporulating layer and growing in size with each passing year.

CHEMISTRY & PHYSIOLOGY

OPHIOCORDYCEPS SINENSIS

Caterpillar Fungus

	SCIENTIFIC NAME	Ophiocordyceps sinensis
Priceless medicine	PHYLUM	Ascomycota
	ORDER	Hypocreales
	FAMILY	Ophiocordicipitaceae
	HABITAT	Grassland

Known to Tibetans as yartsa gunbu(“summer grass-winter	However, researchers long puzzled over the association of
worm”), the Caterpillar Fungus has a long-standing history	the fungus and its host, the ghost moth (Thitarodes armoricanus
in local medicine and culture. Texts describing it date from	and related species). Larvae of these species feed on grasses
at least the fifteenth century and probably hundreds of	and other plants of the high elevation Himalayas, before
years prior to that under other colloquial names.	digging several inches into the soil to overwinter as pupa and
	emerging in the spring as adults. The question was: how did
Today, Caterpillar Fungus (Ophiocordyceps sinensis) is nearly	the spores of Ophiocordyceps sinensismanage to find and infect
as central to Tibetan life as the yak, and in the spring	the all-too-rare larvae of these moths?
everyone heads for the alpine pastures in search of the elusive	The answer, it was discovered recently, is that the fungus
fungus. Indeed, Ophiocordycepsaccounts for 10 percent of the	lives endophytically inside many species of grasses and
entire gross domestic produce of Tibet, and around 50-90	flowering plants in the habitat, upon which the larvae feed.
percent of the income of rural Tibet, depending on regional	Further evidence supports the theory that the fungus infects
productivity. Most of the fungus goes to China where it can	the insect host via its digestive system and undoubtedly lives
command astounding prices in medicine shops—nearly	for quite a long time inside its host before killing it.

US$25,000 per pound (roughly US$50,000 per kg).

Caterpillar fungus lifecycle

Spring: Fungal stroma emerges

from soil (A) and becomes visible. Small chambers, termed perithecia, embedded in stroma release spores (B) that germinate and infect grass plants or caterpillars, or both.

Caterpillars feed on grass plants			 Springtime emergence for the
throughout the season but go		D	Caterpillar Fungus. It’s astounding to
underground to pupate (C).			think that this fungus has developed the
Infected caterpillars are not killed			ability to not only subvert the immune
immediately but continue burrowing			system of plants, but also of insects, in
(D) until they come to rest with the			order to complete its life cycle. Others
head pointing upward (E).			of its kind (the order Hypocreales) also
	A		are capable of jumping between hosts
		E	of different kingdoms—from plants to

animals, fungi to animals, etc.

CHEMISTRY & PHYSIOLOGY

FUSARIUM GRAMINEARUM

Mycotoxin

	SCIENTIFIC NAME	Fusarium graminearum
	PHYLUM	Ascomycota
	ORDER	Hypocreales
Producer
	FAMILY	Nectriaceae
	HABITAT	Farmland and urban
Biowarfare agent

Trichothecenes are a large family of chemically	However, the president’s accusations were proved wrong
related mycotoxins produced by various species	by a team of scientists led by Harvard University scientist
of fungi, including Fusariumspecies (especially	Matthew Meselson, who traveled to Southeast Asia to
Fusarium graminearum) and species of Stachybotrys,	investigate. The researchers concluded that the yellowish
Trichoderma, and Trichothecium. Trichothecene	drops found on foliage were most likely produced by
mycotoxin poisonings are mostly food borne—	honeybees, which often leave their nests en masse and
in spoiled or molded grain such as wheat, oats,	produce showers of pollen-laced feces that can cover an acre
barley, or maize (corn)—and can be very dangerous	or more with hundreds of thousands of yellow spots. At the
to humans, livestock, and other animals.	same time, traces of poison that had been found in some CIA
	samples were most likely false positives caused by laboratory
The most famous case involving humans occurred shortly	contamination—a reasonable scenario seeing as the lab where
after the Second World War in the Soviet Union, where it is	the original CIA samples were sent was a mycotoxin-testing
believed that 100,000 people may have been killed by grain	facility that handled tons of grain and other agricultural
contaminated with T-2 toxin. Given their toxicity, it is	commodities laden with mycotoxins. As no chemical
perhaps unsurprising that trichothecenes have been studied	munitions have ever been found, and none of the hundreds
as horrifying weapons of war, but have they ever been used?	of Vietnamese soldiers who were debriefed provided a shred
Certainly former U.S. President Ronald Reagan thought so.	of information that suggested the use of a weapon remotely
During the summer of 1975, two years after the USA ceased	resembling yellow rain, it would appear that the “evidence”
military involvement in Vietnam, reports began trickling out	was based on flawed intelligence, faulty data, and a
of the region that Laos government forces were using	misunderstanding of basic science.

Soviet-supplied chemical weapons to terrorize the Hmong people (who had fought against the Communists). Thousands of refugees who had been driven from their mountain sanctuaries described exposure to a “yellow rain” that caused bleeding from the nose and gums, blindness, tremors, seizures,

and death. Samples of yellow rain were collected secretly by

 Electron micrograph of plant

the CIA and analyzed, leading President Reagan to accuse

pathogen Fusarium graminearum

spores and inset photo of yellowed

the Soviet Union of supplying weaponized trichothecene

wheat plant showing signs of infection

mycotoxins to its Vietnamese and Laotian allies.

(alongside healthy green plant).

CHEMISTRY & PHYSIOLOGY

MASSOSPORA CICADINA

Flying Saltshaker

	SCIENTIFIC NAME	Massospora cicadina
	PHYLUM	Zygomycota
	ORDER	Entomophthorales
Fungus
	FAMILY	Entomophthoraceae
	HABITAT	Forest and urban
Gruesome reproduction

No matter where you live, you are probably familiar	rest of its few remaining days frenetically flying and
with the song of the cicada. Cicadas are rather large	attempting to copulate with unwitting partners, who then
flying insects belonging to a huge group (more than	become infected.
,000 species) of true bugs or hemipterans. They spend	The fungus that germinates in the secondarily infected
most of their lives underground as larvae, sucking the	host will produce sexual spores that can remain dormant in
juices from tree roots, before emerging in the summer	the soil for many years—lab research shows they will not
to drive humans crazy with their loud and incessant	germinate for, you guessed it, 13 to 17 years, or more. In the
drone. Yet despite being aural irritants, cicadas have	final stages of infection, the terminal segments of the infected
an amazing story, and an equally strange fungal	cicadas fall off and as they fly around, they resemble flying salt
symbiont that goes along for the ride.	shakers, sprinkling the earth with spores that will lie in wait

for the next generation of hosts.

Magicicadais a small cicada group known only from eastern North America, which does things differently. Unlike other cicada species they do not emerge every year. Instead, they live underground for exactly 13 or 17 years (depending on the species), before emerging in a coordinated fashion. In a year when the “periodical” cicadas emerge, their numbers reach nearly 1 billion individuals per acre during their three- to four-week breeding season.

Although predators gorge themselves on the bugs, they consume only a tiny fraction of them. A much greater risk to the Magicicadais the fungus Massospora cicadina. This zygomycete fungus latches on to cicada nymphs as they crawl through their chimneys before emergence. Fungal hyphae grow throughout the host’s body, and its abdomen fills with

conidia. The fungus produces psilocybin (a psychedelic) and

An unwitting adult cicada hosts a

cathinone (an amphetamine), causing the host to spend the

lethal pathogen. As the fungus goes into

reproduction mode, the terminal segments of the host’s abdomen falls off and spore-laden hyphae are exposed.

SAPROBES &

PARASITES

SAPROBES & PARASITES

Our rotten world

Fungi play diverse roles in the ecosystem of the planet, and how they derive their nutrition is just as varied. Fungi cannot “make their own food” in the same way as plants that use sunlight as their energy source, or the bacteria that derive energy from the oxidization of inorganic compounds. Instead, they rely on other organisms.

OUR ROTTEN WORLD

ر Decomposition by brown rot fungi results in blocky brown chunks of woody debris.

× Facing page shows white stringy debris resulting from white rot fungi decomposition.

Like us, fungi are heterotrophs, which means they get	wood-rot fungi, the buildup of coal deposits decreased
energy and nutrition from other organisms, either	dramatically during the Permian Period.)
saprotrophically (by decomposing dead organic	If you examine a fallen tree in a forest you will find
material) or biotrophically (by living as a symbiont of	a tiny ecosystem. In death, all of the tree’s organic
another living organism). The term “symbiont” is often	matter—most likely tons of carbohydrates and proteins
mistakenly used to mean that both organisms in an	and other building blocks of life—is sitting there for
association benefit from the association, but this is not	the taking, for any organism with the ability to break
necessarily the case—symbionts, by definition, are	down wood. Simple single-celled bacteria can ingest
merely two organisms that live in a close association.	sugars that are sitting on the surfaces of the wood,
Of course, symbioses can be mutualisms, where both	while slime molds ooze over and engulf them. Fungi
organisms benefit, but parasites and pathogens are also	are well adapted to breaking down wood using cellulase
symbionts, and these associations are to the detriment	enzymes, and wood boring beetles, wood wasps, and
of the host (there are also commensalisms, where one	other arthropods can all feed on wood that has been
organism benefits, while the partner neither benefits	inhabited and degraded by fungi (much of the time,
nor suffers). We will explore mutualistic fungi in the	the fungi were inoculated into the wood by their insect
following chapter—here we will concentrate on	partners to start with). At the same time, birds and
the saprobic and parasitic lifestyles of fungi.	mammals tear through the wood in search of
Phylogenetic analyses suggest that fungi capable of	arthropods to dine on, while other members of the
rotting woody plants didn’t come on to the scene until	forest make homes out of cavities in the wood.
the end of the Carboniferous Period (360-290 MYA),	The circle of life for that single tree is complete
which is quite a bit after the evolution of woody plants.	when the log serves as a nurse tree for seedlings,
So, instead of decomposing, all of that early organic	or is decomposed entirely back into soil.
matter piled up and changed through a process of	The decomposition of carbohydrates and other
chemical reduction, becoming fossilized and turning	organic matter is pretty much the same chemical process
into fossil fuels like coal. (With the proliferation of	as photosynthesis, but in reverse. During photosynthesis,

SAPROBES & PARASITES

Circle of Life

The food web of any environment consists of many abiotic factors (water, sunlight, temperature) and

biotic contributors like plants and

COin the

atmosphere

animals that are readily visible. Just as important are the decomposers like

Respiration

Photosynthesis

fungi that are often invisible, breaking down dead organic matter on the surface as well as underground.

Decomposition

Soil

Decomposition of dead organic matter

Decomposition Decomposition of dead organic matter

plant chlorophyll captures the red and blue wavelengths	Fungi (and you and I) do the reverse during
of sunlight (green is not much used and is reflected,	aerobic respiration: six-carbon sugars, such as glucose,
which is why plants appear green). That sunlight is	are broken down for their hydrogens, and breaking the
converted into energy to “fix” single carbon molecules	hydrogen bonds releases the energy that our cells use
(the very plentiful carbon dioxide molecules in the	to do what needs to be done. The single carbons that
atmosphere), creating growing chains of carbons and	are left over are mostly useless to us and are given off in
hydrogens—literally the carbohydrates of plant matter.	their most oxidized form as carbon dioxide. When the
It is bewildering to think that pretty much allthe plant	hydrogens are used up, they are released as waste as well,
matter you see before you, from the tiniest seedling to	in their most oxidized form as water—urine is mostly
the mightiest redwood tree, came from the air.	this waste water, plus some other dissolved wastes too.
Powered by the sun, the carbon fixation reaction
is carried out by an amazing enzyme with an equally	WOOD ROTTERS
impressive name: ribulose-1,5-bisphosphate	Plants are mostly cellulose and lignin. Both are difficult
carboxylase-oxygenase (or RuBisCO). This is thought	to break down and require arsenals of enzymes and
to be the most common enzyme on Earth and, one by	other machinery. For the most part, wood-degrading
one, it fixes carbons into six-carbon sugars that are	fungi are good at breaking down one or the other, but
linked together to form cellulose and other	they’re mostly after the same thing: cellulose. Fungi that
carbohydrates from which plants grow.	break down cellulose directly are called “brown rot”

fungi, as they leave behind the brown lignin in the wood. Lignin is a polymer of very tough ring molecules that strengthen wood, but once the celluslose has been removed the wood cracks and falls apart as cubes—the reason topsoil and humus layers are dark brown is because much of that material is lignin that proved too difficult for microbes to break down. Examples of brown rot fungi are the polypores Laetiporus, Phaeolus schweinitzii, and Fomitopsis.

In contrast, the “white rot” fungi have powerful peroxidase and laccase enzymes that break down lignin, bleaching the wood and initially leaving stringy white cellulose behind. Although there is evidence that these fungi can decompose lignin completely to carbon dioxide, many researchers suggest that the fungi are mostly removing it from the woody pulp to better get at the cellulose. White rot fungi found worldwide include polypores such as Inonotus, Ganoderma, and Trametes, as well as Pleurotus, Armillaria, and the popular cultivated Shiitake, Lentinula edodes.

HARNESSED ENZYMES

The destructive power of white rot fungi can be put to good use, though: the power to bleach wood pulp of lignin makes the white rot fungus

Phanerochaete chrysosporiumimportant to the paper industry as an

environmentally benign replacement for harsh synthetic chemicals.

س Wood rot fungi can decompose and weaken the interior of a standing tree (known as heart rot) until it ultimately breaks and falls over, leaving a mushroom-covered stump.

SAPROBES & PARASITES

ر The result of several years’ decomposition by heart rot fungus is shown in a cut log.

ز The tiny Earpick Fungus (Auriscalpium vulgare) decomposes small conifer cones (pictured on the cone of a Douglas-fir). That’s it—that’s its habitat. The forest floor can be covered with cones, and few organisms can decompose them, so this fungus has a niche without much competition.

Many wood rot fungi don’t wait for trees to die	LEAVES AND LAWNS
before launching their assault, and living trees often	While dead and fallen wood is clearly a source of
sport big fruitbodies of shelf fungi (polypores). This is	exploitable nutrition, so are all the other parts of the
because most of the tree is heartwood—dead inner	tree. Leaves that fall to the ground are composted
wood—and only the outer layers, just under the bark,	quickly, and many popular edible mushroom species—
are living tissue. Therefore, all it takes is a wound to	such as the beautiful lilac-colored Blewit (Clitocybe
disrupt the integrity of the bark, and heart rot can	nuda)—are reliably seen in the fall wherever leaves
ensue (similarly, butt rot happens at the base of the tree).	accumulate. At the same time, Lophodermium pinastriis
Heart rot can proceed for many years without	highly specialized to decompose conifer needles, just
really having much negative effect on the tree; the	as the strange-looking Earpick Fungus, Auriscalpium
heartwood is dead anyway and, up to a point, the	vulgare, is highly specialized to rot pinecones. Both are
strength of a hollow pipe is about the same as a solid	commonly seen in boreal forests worldwide.
pipe. So, while it is easy to assume a large bracket fungus	There is so much competition for the organic matter
hanging off a tree is a parasite, few polypores are true	that falls from the forest canopy that some fungi create
parasites of living tissue. In most cases, an otherwise	a sort of “net” to catch the jettisoned debris before it
healthy tree takes measures to contain these heart rot	reaches the forest floor. Members of the Marasmius
fungi and prevent them from invading living tissue.	crinis-equigroup produce strong rhizomophs above the
While we are most familiar with the big	ground and even among the canopies of rainforest trees
basidiomycete wood rotters, upon close inspection	in the tropical Americas and western Africa. As the
we also see many ascomycete white rot fungi as well.	networks of rhizomorphs become more extensive, they
Many small crusts and bumps on twigs and fallen logs,	trap leaf litter and other debris raining down from
like Daldinia and Xylariamay not seem impressive, but	above as a food source for the saprobic fungi.
are mighty agents of wood decay. Also, it’s by no	Birds actively collect these rhizomorph cords to use
means a rule, but in general the brown rot fungi are	as a nest-building material. This works out very well for
more likely found on conifer wood, while the white	the fungus, as they continue to grow and digest the nest
rot fungi mostly attack hardwoods.	after the owner vacates. The litter-trapping fungi

SAPROBES & PARASITES

rhizomorphs also benefit the birds, as they increase the	resistant—they have thick walls designed to help them
nest’s structural support, while simultaneously decreasing	survive passage through an herbivore’s intestinal tract,
its moisture content. Additionally, fungi of this group	and this also makes them conducive to fossilization.
produce antibiotic compounds, which may provide an	Sporormiellais an ascomycete that produces dark,
adaptive benefit to the birds and their nestlings.	uniquely shaped spores that are unmistakable in soil
Unlike fallen wood or damp forest leaves, a garden	sediments, even from thousands of years ago. These
lawn or other expanse of grasses is much more prone to	spores are an indicator of changes of vegetation
periods of drying. However, for fungi that are adapted	throughout history, with accumulations of Sporormiella
to this type of habitat, a great deal of cellulosic	spores correlating to an abundance or absence of
nutrition awaits. A lawn may seem like an unlikely	herbivores. Using these fungi, scientists are able to
place for a mycophile, but it can be a great location to	determine when mammalian megafauna dominated
observe the activity of fungi. Some, such as the meadow	North America, and when they started to decline due
or field mushrooms (Agaricusspecies) and Marasmius	to factors such as a changing climate and Paleo-Indian
oreades, cause noticeable green arcs or rings—“fairy	hunting pressures at end of the Pleistocene. Following
rings”—in grassy areas where they are actively growing.	the last Ice Age, for example, we can see that the
The nature of these rings is explained a little later, but	numbers of dung fungi in North America remained
as you will see, these ecosystem engineers are doing	low until the seventeenth century, when European
much more than decomposing dead grass matter.	settlers arrived with livestock, and by extension dung.

COPROPHILOUS FUNGI

The undigested plant matter that passes through grazing animals is mostly cellulose, and therefore highly nutritional for coprophilous (“dung-loving”) fungi. Since the animal did much of the mechanical work to grind and partially break down this material, being the first to colonize dung before competition arrives has led to interesting specialization. Cheilymenia coprinaria (C. fimicola) spring up first, followed by basidiomycete mushrooms including Deconica coprophila, Stropharia merdaria, and Panaeolus semiovatus. Various Conocybes and Coprinelli species are also common.

For as long as there has been dung lying about, ready to be exploited, there have been coprophilous fungi. We know this because their spores are found deep in soil layers, lake deposits, and permafrost. The spores of dung fungi are particularly tough and

ز Tiny fruitbodies of the ascomycete

Cheilymenia coprinariaon moose dung in Finland.

OUR ROTTEN WORLD

Sporormiella has borne witness to the arrival of humans and the extirpation of large herbivores around the world, from the flightless moa of New Zealand a few hundred years ago, to the megafauna of Madagascar in AD 200, and the megafauna of Australia 40,000 years ago. In each case, as the large herbivores vanished so did Sporormiella from the layers of soil. At the same time, wherever (and whenever) humans have introduced domesticated grazing livestock, we see a coincident increase of Sporormiella spores in soil sediments.

It is not just the waste from large animals that can host fungi—fungi can also tap into seemingly inconsequentially small excretions from insects. The sugary “honeydew” (undigested plant sap) that passes through many sucking bugs, such as aphids, will be colonized readily by black molds. These saccharophilic “sooty molds” will discolor anything beneath a tree where aphids are feeding and honeydew rains down, including the white wooden swing of my childhood, much to my mother’s great frustration!

³ The very small basidiomycete

saprobe Marasmius crinis-equi looks delicate but their rhizomorphs are quite tough, often wrapping around plants (inset image), and even spanning distances between forest plants to ensnare debris falling from the forest canopy.

OUR ROTTEN WORLD

SARCOPHILOUS FUNGI	sources of ammonia can form a suitable habitat.
Although many fungi decompose plants, some are	Sagara discovered that fruitings of Hebeloma radicosum
“sarcophilous,” which means they are keenly adapted to	could reliably be used to locate the dens of moles,
decomposing animal carcasses, or any other organic	where the mycelial source was the mammal’s latrine.
matter that is highly nitrogenous or ammoniated. The	Hebeloma sarcophyllum, H. syrjense, and H. radicosumare
corpse may hardly be cold when the Corpse Finder	found across the Northern Hemisphere, but are all
(Hebeloma syrjense) and Ghoul Fungus (H. aminophilum)	uncommon species, while H. aminophilumis known
set to work, and it is entirely likely that spores of these	only from Australia. They all grow in association with
poorly understood fungi are transported to corpses via	decomposing animal remains and are sometimes
flesh flies of the family Sarcophagidae, or other	mentioned for their use in forensic science.
arthropods. Fungi that are associated with nitrogenous	What the sarcophilous fungi show us is that no
matter include Mitrula, Laccaria, Rhopalomyces,	matter what the source of nutrition is, and no matter
Amblyosporium, Ascobolus, Tephrocybe, Peziza, Coprinus,	how difficult it is to break down, there is a group of
Crucispora, and Byssonectria, among others, but the	microbes in nature that have figured out how to do it.
association is not always clear. Many of these fungi—	Some components of animals persist long after death,
including Hebeloma—are mycorrhizal.	including fur, feathers, and horns, which are
Much of what we know of this group of fungi	constructed of keratin. Keratinized material is so tough
comes from the Japanese mycologist, Naohiko Sagara,	that only a single group of fungi can decompose it: the
who made them his specialty. Sarcophilous fungi can	order Onygenales. Undoubtedly the most unusual (but
often be encouraged to fruit by burying urea or other	least understood) genus of the group is Onygena, which
compounds that decompose to ammonia in the woods,	is profiled on page 126.

so in the absence of a fresh corpse we know that other

ر The tiny Mitrula paludosais

uncommonly seen across northern Europe—who goes looking for mushrooms in standing water? The Matchstick Fungus is found on decaying leaves, conifer needles, and fallen catkins in temporary pools, swamps, and sphagnum bogs. Mitrula elegansof North America is similar and also rarely encountered.

ز A mammal horn adorned with tiny fruitbodies of Onygena equina.

SAPROBES & PARASITES

Parasites of animals

If we learn anything about fungi in school, books, and films, it’s that they are decomposers. But while it is true that many fungi are masters at decomposition, the majority are biotrophs, living in obligate association with other living organisms. Indeed, when it comes to life on the planet— Prokaryotes and Eukaryotes combined—most is parasitic.

Mercifully, there are not many fungal parasites of humans	Cutaneous fungi are often called dermatophytes,
and other mammals, and this is a good place to begin	due to their propensity to live on skin. Most of them
our discussion. Fungi that are most likely to afflict us	(as well as the truly pathogenic fungi) belong to the
are cutaneous (stay put on the skin), where they mostly	Onygenales, which is a cosmopolitan group of
dine on dead skin or sebum, the oily exudate from the	ascomycetes that are among the few microbes that can
pores of our skin. A few fungi can grow in a subcutaneous	break down keratin. Many of these fungi are found
manner (beneath the skin), causing a local infection,	only on humans, and are known clinically as tinea
and there are a few opportunist fungi that can cause	(and colloquially as “ringworm”). The afflictions they
complications inside the body if something gets out	cause go by various names, depending where on the
of balance with your regular resident microbial flora,	body they occur—tinea pedis(athlete’s foot), tinea capitis
or if you become immunocompromised. There are also	(ringworm of the scalp), tinea cruris(jock itch), and so on.
a few fungi that are serious pathogens of humans.	Of course, there is no actual worm involved, so you

think of tineaas a fairy ring on your skin. As the fungus grows outward through the outermost layers of (mostly) dead skin, it causes a slight irritation that manifests as a reddened zone. This irritation causes increased skin flaking, which provides the fungus with more food, as well as producing dead skin that flakes away and helps spread the fungus to additional hosts.

The most common dermatophytes are of the genera Microsporum, Trichophyton, and Epidermophyton, but the most notorious true pathogens belong to the

ر Microscopic findings showing

macroconidia of Microsporum canis, a ringworm infection in dogs.

ز A digitally-colored electron micrograph of the cells of a Malassezia species, which grows as a yeast, one cause of dandruff.

SAPROBES & PARASITES

ر Biopsy of human liver showing histoplasmosis. Stained cells show small bright red clumps, the pathogen, as well as granulomas, darkly stained.

ز Hyphae and sporophores of Sporothrix schenckiiseen with microscopy and digital coloring.

ط Candida albicansisolated from a vaginal swab. Stained and viewed under microscopy, hyphae and chlamydospores of the fungus are clearly visible (blue-black color); the pink blobs are healthy human epithelial cells.

genus Ajellomyces. These are much better known by	infection, but in rare cases it can spread via the lymph
their anamorphic, or asexual forms, though: Histoplasma	nodes to form serious lesions inside its victim.
capsulatum, Blastomyces dermatidis, Coccidioides immitis, and	Other yeasts are common on our bodies as resident
Paracoccidioides brasiliensis.All of these fungi live freely in	flora. Likely the most dominant fungus of all is a yeast:
soil and organic matter, and can enter the body via	Malassezia. This fungus is the leading cause of dandruff,
inhalation, sometimes causing serious problems.	but is common over other parts of the body as well. It
Histoplasmais found in high nitrogen substrates like bird	is especially adapted to feeding off the sebum that our
droppings, bat guano, and chicken farms; Coccidioides,	bodies produce. In fact, the fungus doesn’t have the
the cause of “valley fever,” is mostly found in arid	ability to store fats—it likely lost the ability and now
Southwest soils; Paracoccidioidesis known only from	relies entirely on its host.
Central and South America; and Blastomycesis found	Another common yeast is Candida albicans, which
in soil and plant debris.	is found in the GI tract and other regions. This fungus
One subcutaneous pathogen that is worth	can grow just about anywhere on the body if
mentioning is Sporothrix schenckii, which is the cause	conditions are kept moist, and has an interesting
of “rose handler’s disease.” This fungus is somewhat	lifestyle. Normally, it grows as a budding yeast, but on
common on plant material, including sphagnum moss,	the skin or in the mouth cavity the fungus goes into
which is used in greenhouses and occasionally in	invasive mode, growing as a mycelial form. Toxins
floristry shops. It is only able to enter the body by way	produced by the fungus help it to invade tissues and are
of damage to the skin (typically by pokes from thorns	an irritant, causing rashes—“thrush”—that are familiar
or sharp tools), but once inside it switches gears to	to most of us. Candidiasis inside the mouth can be
grow as a yeast. To start with it causes a simple local	particularly painful.

SAPROBES & PARASITES

Parasites of plants

Fungi are by far the most successful pathogens of plants: around 60-70 percent of all plant pathogens are fungal species. Pathogens may start out as biotrophs, subsisting on the tissues and resources of a living host, but may then switch to being saprotrophs, continuing to live saprobically off the dead host’s tissues.

An intact, healthy plant is largely impervious to

microbial attack. It is protected from the outside by a tough cuticle and waterproof layers of wax, while the perennial tissues (of trees, for example) may build up

ش Gymnosporangium juniperi

corky dead layers for added protection. Plants are so

virginianae is a rust fungus commonly

seen around the home.

good at fending off pathogens that even the most

PARASITES OF PLANTS

Botanical synecdoche

An individual plant is an entire ecosystem. All parts of a plant support macroscopic (e.g., arthropods)

and microscopic (e.g., nematodes)

Smut fungi

animals, as well as all manner of microbes including fungi, bacteria, and viruses. All are biotrophs, with some living as mutualistic partners

with the plant host (e.g., arbuscular

Begomovirus

Powdery mildew

fungi and rhizobial bacteria).

Bacterial spot

Crown gall

Figivirus

Root-cyst Rhizobia nematode

Arbuscular

Root-knot nematode

successful fungal plant pathogens are only able to attack	plants is an important line of defense and is widespread
certain groups of plants. Consequently, many plant	throughout the plant kingdom.
pathogenic fungi are highly specialized, and will	Because biotrophic fungal pathogens require a
attack only a single plant species, or possibly just certain	living host, they tend not to kill cells, but instead make
varieties of a species.	their way through the cell wall without disrupting the
To breach the outer protective layers of plants,	cell membrane. Plant materials in the cytoplasm may
fungi deploy an arsenal of chemicals, as well as physical	continue to move across the cell membrane to other
weapons. For fungi to penetrate plant tissues, they must	plant cells, only to be stolen by the fungal parasite. To
first adhere to the surface of their host. To achieve this,	help them tap into the plant cells, many groups of
a hypha makes contact and forms a flattened	biotrophic fungi have special structures with elaborate
“appressorium,” a sort of bulb at the hyphal tip that	ornamentations or branches at their tips, which increase
increases the surface area. The next step involves	their absorptive surface area.
powerful chemical enzymes that erode the plant surface	Biotrophic fungal pathogens often produce plant
layers, or possibly the production of a hardened	growth regulators (sometimes called “plant hormones”)
“penetration peg” that exerts pressure and forces the	that mimic those produced by their hosts. These
hypha through a tiny opening in the outer plant layers.	compounds can alter the physiology of the plant to the
Once through the plant’s defenses, fungal hyphae	benefit of the fungal pathogen. Some of these plant
can enter the plant and grow between the plant cells, or	growth regulators cause noticeable symptoms on the
may kill the tissues outright. Often, the plant mounts an	plant host, including stunting, overgrowths, galls, “hairy”
“immune response,” whereby chemicals are released to	or excessive root branching, “witches’ brooming” or
cause plant cell death—a sort of localized suicide to	excessive branching, stem or other malformations,
contain the infection. This hypersensitive reaction of	defoliation, and even the suppression of bud growth.

SAPROBES & PARASITES

Rosetting is a manifestation where excessive leaves are	TYPES OF PATHOGENIC FUNGI
produced that may even resemble a flower head. Some	Plant pathogenic species are found among most major
pathogenic fungi go so far as to create “pseudoflowers”	groups of fungi, including the chytrids, which are some
of rosettes to help get their spores transmitted to	of the most primitive. During wet periods, the
another host plant.	zoospores of chytrids can swim through soil with their

whip-like flagella to reach their plant hosts. Aquatic chytrids, are specialized to prey upon plant pollen, latching onto pollen grains and boring through to get at the rich reserves inside.

The vast majority of fungi are ascomycetes and undoubtedly most plant pathogens belong to this group. They often go unnoticed given their diminutive

س Honey mushrooms (Armillaria

size, with many producing tiny fruitbodies on the

species) fruiting at the base of a tree

spell doom for the plant.

plant’s surface.

PARASITES OF PLANTS

HUMONGOUS FUNGUS

Some fungi produce thickened, cord-like rhizomorphs to facilitate their movement between sources of substrate. Armillariaspecies are particularly efficient at moving from one cut stump to the next in a forest, by creating long rhizomorphs. These cords are black; being melanized undoubtedly protects them from damaging sunlight as they span areas of the forest floor. They are most noticeable when bark falls off a rotting log, revealing the mushroom’s “bootlaces.” As well as being an efficient saprobe, Armillariaspecies are also aggressive pathogens; defoliation by Gypsy Moth (Lymantria dispar) or other stressors weakens trees and increases their susceptibility to Armillaria Root Rot disease. Megacollybiais another cord-forming saprobe of stumps, as well as branches and other fallen debris of the forest.

Butt rots—fungal infections at the base of trees—	pathogens kill and decay roots, decay inner wood in
are quite common in forests, and probably even more	the butt, and often kill sapwood and cambium in the
so in urban areas where trees are damaged by people,	root crown. The pathogen can spread from infected
vehicles, or other machinery, allowing all manner of	roots to the healthy roots of neighboring trees.
pathogens to enter. In the forest, butt infections result	Commonly seen butt rot fungi include some pretty
in a direct loss of wood volume and harvestable timber,	large polypores, including Inonotus, Ganoderma, Grifola,
but they may serve a positive role in creating clearings	Laetiporus, Meripilus, Onnia tomentosa, Heterobasidion
and favorable woodpecker habitat. However, in urban	annosum,and Phaeolus schweinitzii.
situations, these infections seriously weaken the	Around the home, a common plant pathogenic
foundation of the tree, making it more susceptible to	fungus is Venturia inaequalis, which causes Apple Scab.
breakage and wind throw; trees with these infections	We know that this fungus has been a problem on apples
are hazards and their timely removal is necessary for	for a long time, as symptoms of the disease can be
public safely. Many fungi cause butt infections, and	observed on fruit in paintings from the fifteenth and
almost all of them are basidiomycetes. In general, these	sixteenth centuries—perhaps the earliest record is seen in

SAPROBES & PARASITES

Michelangelo da Caravaggio’s painting Supper at Emmaus (ca. 1600). Initially, all commonly grown apple varieties were susceptible, and there were no chemical treatments to prevent the disease until the late 1800s. At that time, copper- and sulfur-based fungicides provided protection if applied prior to infection, although the chemicals caused substantial damage to the apple tree’s foliage. Today, Apple Scab causes greater economic losses of apples in North and South America, Europe, and Asia than any other disease, despite the highly effective chemicals and the resistant apple

س Painting of Caravaggio’s Supper

varieties that are available. The fungus also attacks

at Emmaus, with inset showing detail

of Apple Scab on fruits.

other fruit trees in the Rose family.

ز Fruit and leaves infected with

Venturia inaequalisis an ascomycete fungus in the

Venturia inaequalisshowing discolored

order Pleosporales. Like most other ascomycetes,

blotches

PARASITES OF PLANTS

V. inaequalisreproduces asexually by conidia; this stage	heteroecious (requiring different and distinct
is known as Spilocaea pomi. Conidia are produced soon	hosts for different lifecycle states), whereas smuts are
after infection and are disseminated by wind and	monecious (completing their lifecycles in a single host).
splashing rain, quickly spreading the infection. Multiple	There are around 7,000 rust species and an
cycles of conidial production and infection can occur	estimated 168 genera worldwide among this group of
within a single growing season, which can lead to	organisms, and with so many of them it is sometimes
severe disease outbreaks termed “epiphytotics.” Severely	difficult to put the group into perspective. Most rusts
infected leaves or fruit will often drop from the tree	have up to five spore stages (spermagonia, aecia,
prematurely, with lesions on the fruit making them	uredinia, telia, and basidia in successive stages of
look scabby and unappealing. Sexual reproduction results	reproduction), although others have as few as three
in spore-bearing cells (asci) being produced within the	spore stages. They are all obligate parasites, meaning
leaf tissue. In spring, when the leaves become wet, the	they can only grow on a living host, but most of the
hyphae swell and protrude from the surface of the leaf,	rust fungi that infect trees have spore stages on two
forcibly ejecting ascospores and completing the lifecycle.	completely unrelated hosts.
	Rusts of cereal grains typically have a broadleaf
RUSTS AND SMUTS	host plant for part of their lifecycle. In the case of
Rusts and smuts are basidiomycetes, so are close	Wheat Stem Rust the alternate host is barberry plants,
relatives to mushrooms. All are parasites of plants, and	including the invasive Berberis vulgaris, while for Crown
together they form very large and fascinating groups	Rust (Puccinia coronata avenae) it is the thorny buckthorns,
of fungi, even though most are physically pretty small.	including the invasive Rhamnus cathartica. In temperate
The rusts are especially interesting, as many of them are	areas of Europe and North America, the broadleaf

alternate host is an important source of initial inoculum for cereal fungi.

A tremendous amount of effort is put into studying rust fungi, as they are responsible for many of the most economically costly diseases of crop plants worldwide. The fungus Puccinia graminis tritici(and two other

species) causes rust of wheat plants, which results in annual losses of more than 1 million metric tons of wheat in North America alone; in severe epidemic years the losses can reach tens or hundreds of millions of tons. As the world gets more crowded, and therefore hungrier, this fungus will almost certainly be the cause of mass famines and possibly even wars.

SAPROBES & PARASITES

Life Cycle of Wheat Stem Rust Puccinina graminisrequires two very different host plants to complete its life cycle and produces several different

spore types in a single season.

Pycnidium (spermagonium) with

receptive hyphae and spermatia

Wheat stem with

Basidiospores

urendiniosporangia

germinate on barberry leaf

EARLY SEASON

Plasmogamy

Aecium with

Basidiospores

aeciospores

Meiosis

Close-up of wheat

LATE SEASON

plant containing

Teliospores

urendiniospores

in telium on wheat plant

Germinating

teliospore

Karyogamy Wheat stem with teliosporangia

Human civilizations have struggled with this disease	to North America in the early twentieth century,
for centuries. The Romans tried to appease the fungal	arriving on white pine seedlings from France. The
gods with “robigalias”—elaborate ceremonies where a	fungus has a complex lifecycle that requires two
dog was sacrificed in an effort to stave off the rust-colored	hosts—a white pine and, most commonly, a currant
“red fire” that annually descended on their fields and	or gooseberry plant (Ribesspp.). This disease is very
consumed their wheat. Today, we try to control rust	important economically, as it affects some of the most
fungi by breeding resistant crop plants, but this is a slow	valuable timber stocks in the USA. To try and break the
and tedious process. It is also a temporary one as, to date,	disease cycle the government launched a program in
all resistance has been broken through evolution, as	the 1920s to eradicate wild currant and gooseberry
ever-more pathogenic strains of the fungus have emerged.	plants from the eastern states. This program lasted
Among the most famous forest tree diseases we find	through to the 1950s, by which time the Ribes
another rust: White Pine Blister Rust. The pathogen,	population was significantly reduced. The federal
Cronartium ribicola, is native to Asia and was introduced	ban on the sale and cultivation of Ribesspecies was

PARASITES OF PLANTS

eventually lifted in the 1960s, although such is	and may be seen across Europe wherever apples
the importance and value of white pine that state	(or crabapples) and junipers coexist. In eastern North
quarantine and eradication laws still exist today in	America, the fungus is very common on Eastern Red
many eastern states.	Cedar (Juniperus virginiana) and can be a destructive
A much more commonly seen disease is Cedar	or disfiguring disease on both the apples and cedars.
Apple Rust, which is caused by the fungus	Quince and hawthorns are also hosts.

Gymnosporangium juniperi-virginianaeand results in weird, alien-like life forms appearing on plants. This fungus (and its close relatives) is widespread across North America and Europe, appearing as jelly-like projections from the stem or branches of living tree host plants, or as ball-like galls with brightly colored

س Reddish pustules of Wheat Stem

jelly projections. Cedar Apple Rust requires two hosts

Rust (Puccinia graminis) on wheat plant.

SAPROBES & PARASITES

CYTTARIA GUNNII

Beech Orange

	SCIENTIFIC NAME	Cyttaria gunnii
	PHYLUM	Ascomycota
	ORDER	Cyttariales
Fungus
	FAMILY	Cyttariaceae
	HABITAT	Forest
Otherworldly reproductive forms

The strange ascomycete Cyttariaare obligate biotrophs	Peterson and Don Pfister determined that species of
of Southern Beech trees in the genus Nothofagus.	Cyttariahad coevolved—and been geographically isolated on
Cyttariaspecies are restricted to the Southern	landmasses—with their respective host species of Nothofagus.
Hemisphere, inhabiting Argentina and Chile in South	Thus, species of Cyttariaand Nothofagushave not actually
America and southeastern Australia, Tasmania, and	moved anywhere at all … they’ve been stuck with each
New Zealand. The relationship of this fungus with its	other since the breakup of Gondwanaland, more than
host remains unclear; if it is truly parasitic, it is only	million years ago.

weakly so, and it may even be beneficial in some way. But that is not the only strange aspect of this fungus.

It was Charles Darwin who first brought this peculiar fungus

 Most of the year, the fungus

resides hidden away inside its tree

to the mycological world’s attention. In 1839 he stopped

host. During reproduction, large

at Tierra del Fuego, at the southern tip of South America,

colorful fruitbodies emerge from gnarly

burls on the trunk and branches.

during his voyage on the Beagle. There, he collected fruitbodies from large cankers on Nothofagustrees, which he sent to the esteemed mycologist Reverend Miles Berkeley, who described the new genus Cyttariain 1842. Field notes about the ascocarp fruitbodies noted that the indigenous people there collected them as food and even made wine from them. Although they might resemble some sort of alien life form, the brightly colored fruitbodies are relatives of

Cross-section of the

morels. Indeed, both are apothecia, a sort of cup-shaped

fruitbody showing

the fertile pits

ascocarp, with sterile ridges separating the fertile areas.

Since it was discovered, almost everything about this

A network of cavities

fungus has been an enigma, from its physiology to its lifecycle,

The young fruitbodies are smooth

to what it’s doing inside the host tree and how it spread

and firm, later developing numerous

fertile pits once the membrane bursts.

across the vast oceans of the Southern Hemisphere. To answer

These pits are initially visible as pale

areas on the stroma surface, but open

the latter question we need to turn to a field of study known

at maturity and can be exposed by

as phylogeography. In 2010, Harvard researchers Kristin

peeling off the surface layer.

SAPROBES & PARASITES

USTILAGO MAYDIS

Corn Smut

	SCIENTIFIC NAME	Ustilago maydis
Prized pathogen	PHYLUM	Basidiomycota
	ORDER	Ustilaginales
	FAMILY	Ustilaginaceae
	HABITAT	Farmland

Looking more like excrement than a mushroom,	anywhere else on the corn plant, it cannot penetrate the
with an unsavory name to match, Corn Smut is a	tough cuticle of the corn plant unless damaged (for example,
conspicuous fungus with an amazing life cycle. Known	by hail, insects, etc.). Damage to plant tissues (natural or
scientifically as Ustilago maydis, this basidiomycete	mechanical) can facilitate infection via sporidial or telial
parasite of corn (maize) plants can be found throughout	hyphae. Thus, outbreaks of corn smut are frequently
warmer regions of North America and Europe.	associated with episodes of hail damage.
Historically, the fungus was common on field and sweet	Although harmful to corn, Corn Smut is edible. It has
corn, but modern corn varieties are resistant; heirloom	long been considered a delicacy in Mexico, where it is
corn is still susceptible, though, as is popcorn and	prepared in all manner of ways, including ice cream (it tastes
Indian corn.	much better than it looks, with flavors of mushroom, corn,
	chocolate, and vanilla). Sometimes called “Mexican corn
All parts of the plant may be infected, but galls are mostly	truffle,” the Aztec’s named it huitlacoche(also spelled
seen on ears because the silk (an extension of the female part	cuitlacoche), which roughly translates to “raven’s excrement.”
of the plant) is receptive to pollination, as well as fungal	However, a personal favorite nickname for it is that of
invasion. As discussed on page **, the lifecycle of smut fungi	myco-raconteur David Arora: “porn on the cob.”

two spore stages. The first is large galls—a mass of black, sooty (“smutty”) teliospores enclosed in a smooth covering of plant tissue. Teliospores overwinter, their germination timed to the reproduction cycle of the corn plant. Teliospores germinate in the soil, giving rise to hyphae with club-shaped basidia; borne on each are tiny basidiospores (“sporidia”). Haploid sporidia alight on corn plants, but are not yet able to infect the host. First they must germinate, growing in a yeast-like manner in search of a partner.

Successful crossing between two different mating types restores the dikaryotic condition. Armed with a full complement of genes, the smut fungus is now infectious—

 Ranging from strange to obscene,

but still needs some luck. If on the silk, the fungus must

the highly visible galls of Corn Smut

reach the ovary before pollination occurs. If the fungus lands

on its host.

SAPROBES & PARASITES

ONYGENA EQUINA

Horn Stalkball

	SCIENTIFIC NAME	Onygena equina
Cadaver composter	PHYLUM	Ascomycota
	ORDER	Onygenales
	FAMILY	Onygenaceae
	HABITAT	Forest and farmland

Soon after a body dies and comes to rest, it starts to	Keratin is a tough structural protein that is highly water
decompose, with microbes attacking from within and	insoluble, and all but impossible to break down. Animals have
without. Depending on the environment and conditions,	a tough time digesting it, which is why cats cough up balls
much of the proteins, fats, and other components are	of their own fur, and many kinds of birds regurgitate an
readily recycled into the stuff of other organisms, but	undigested pellet of fur, bones, nails, and feathers.
not everything. Some parts of all bodies (even you) will	The genus Onygenaconsists of just two species, which are
persist long after death: teeth, tough boney tissues (like	found all over the world. Onygena corvinais associated with
skulls), and anything made of keratin, such as nails and	animal feathers and fur, while Onygena equinais a decomposer
hooves, hair and fur, feathers, and horns.	of the hooves and horns of herbivorous mammals. These

fungi are so keenly adapted to digesting keratin that they can use it as their sole source of carbon and nitrogen.

Horn of plenty

It’s astounding that these fungi can find such an

Resembling tiny mushrooms, Onygena

sporophores may completely cover a mammalian

uncommon food source as hooves or a horn lying on the

horn lying on the forest floor or in a pasture.

forest floor, but they have figured that out too. Like all protein-degrading fungi, species of Onygenaproduce a

Close examination of Onygena

sporophores will reveal that

horrible cadaverous smell (even when grown in culture),

what appears to be tiny

stalked mushrooms are masses

which comes from the release of primary amines, just as

of spores at the tips of

aggregations of hyphae.

when meat spoils or corpses rot. This odor attracts carrion

flies, which the fungus uses to hitch a ride to its next meal. The stalked “fruitbodies” of this fungus are actually aggregates of gymnothecia—cage-like spore-producing hyphae—that get caught on the stiff hairs and appendages of the flies and are deposited elsewhere.

 Extreme closeup of Onygena. The tiny globose masses of spores are just a few times the size of the period printed at the end of this sentence.

SAPROBES & PARASITES

MARASMIUS OREADES

Fairy Ring

	SCIENTIFIC NAME	Marasmius oreades
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Mushroom
	FAMILY	Marasmiaceae
	HABITAT	Urban grassland
Marcescent mushroom

Mysterious green rings are a common sight on large	Many kinds of mushrooms will fruit in a ring,
grassy lawns, golf courses, and even expansive plains	but perhaps the most celebrated of all is the Fairy Ring
areas around the world. These “fairy rings” have been	Mushroom (or Scotch Bonnet), Marasmius oreades. That
a source of fascination and myth for hundreds of years,	Marasmiuscan seemingly appear overnight is due to its
appearing in literature and poetry since the Middle Ages.	marcescent habit—it will dry and wither, but can rehydrate
In fact, some of these early rings may still be alive today,	when moisture returns, whereas most mushrooms are
as there are fairy rings large enough to be seen from the	putrescent and will rot when overmature. Indeed, the name
air, which likely makes them centuries old.	Marasmiuscomes from the Greek for “wither,” while the
	specific epithet means “nymph.”
Stranger still are the mushrooms that emerge in the rings.	Fungal hyphal growth progresses radially outward,
Some of these can reach full size overnight, as if summoned	digesting organic matter in the soil, including dead lawn
by some supernatural force. Fairies, elves, pixies, witches,	thatch. As the available nutrients are exhausted, the trailing
dragons, and assorted amphibians have all been suspected	mycelium dies, while the ring of active mycelium results in
of making this “magic” happen; the Blackfoot of Alberta	greener, taller grass as the plants utilize nitrogen released by
believed they resulted from dancing bison.	the fungal enzymatic action.

Although it was once thought to be a simple saprobe,

feeding off dead and dying organic matter, recent evidence

Fairy ring demystified

suggests that Marasmium oreadesis also parasitic on the roots of

Closer inspection reveals that a fairy ring is composed of three concentric

rings or zones: the outer lush zone (A) where the mycelium is active and	grasses. In addition to cellulases and other enzymes, the fungus
where the mushrooms fruit (B); a middle zone where there may be dieback
	also releases toxins including hydrogen cyanide, which damages
of the grass (C); and an innermost zone of stimulated growth (D) that is often
occupied by plants that have colonized previously bare ground.	root tips and impedes water percolation through the soil.

 Fairy Ring Mushroom, Marasmius oreades, with view of gills.

SAPROBES & PARASITES

HYPOMYCES LACTIFLUORUM

Lobster

	SCIENTIFIC NAME	Hypomyces lactifluorum
	PHYLUM	Ascomycota
	ORDER	Hypocreales
Mushroom
	FAMILY	Hypocreaceae
	HABITAT	Forest
Mushroom parasite

The Lobster Mushroom is a strange fungus that is	The transformation of a “lobsterized” mushroom is dramatic,
prized by many as a choice edible. This “mushroom”	as it involves color, smell, and taste. Once fully matured, the
is actually two fungi species wrapped up in a single	fruitbody tissue is almost entirely of the parasite fungus and
package: the first is a Russulaspecies, and the second	becomes delicious culinary fare; until then, the Russulacan
is Hypomyces lactifluorum, which is a parasite of the	range from bland to acrid hot and unpalatable, depending
Russulamycelium growing underground. When it’s	on where it is collected.
time for mushroom formation the parasite takes control.	While the Lobster Mushroom is known from North
The resulting monstrosity produces no Russulaspores—	America, Europe, and Asia, this is just one species of a very
instead, Hypomycesuses it as a launching pad for its	large genus of mycoparasites. All Hypomycesspecies are
own spore production.	pathogens of other fungi and attack many major groups of
	mushrooms including Amanitas, coral fungi, and Auricularia
	(Wood Ear). One of the most widespread is the Bolete Eater
Seeds of destruction	(Hypomyces chrysospermus) of Australia, Eurasia, and North
Hypomyces species don’t produce mushrooms	America, while Hypomyces luteovirensproduces beautiful

of their own, but parasitize fruitbodies of other

fungi and turn them into their own sporophore.

green lobsters of Russulaand Lactarius. Some Hypomyces

Under the microscope, the spores have tapered

parasitize polypores.

ends and are easily recognized.

As they are unable to make mushrooms of their own, Hypomycesco-opt the mushroom-making machinery of their host. Upon close examination of the Lobster Mushroom’s beautiful red-orange skin (the source of the name) you will see bumps—those are the tops of perithecia, pear-shaped chambers buried in the fruitbody tissue. The perithecia blast ascospores into the air and may even coat the mushroom in white powdery spores.

 Looking like something from another planet, Lobster Mushrooms have the color, and the seafood aroma, of their namesake.

SAPROBES & PARASITES

CHLOROCIBORIA AERUGINASCENS

Green Stain

	SCIENTIFIC NAME	Chlorociboria aeruginascens
Prized by artisans	PHYLUM	Ascomycota
	ORDER	Heliotiales
	FAMILY	Chlorociboriaceae
	HABITAT	Forest

Long before modern materials and wood stains were	of weakening by fungal activity, and it is therefore devalued
developed, woodcrafters were skilled at inlaying small	for manufacture, furniture, or paper, but “green oak” is a
pieces of different woods to create mosaics and trompe	n exception to this rule—the color change increasesthe
l’oeil images on furniture and other works of art (a	wood’s value.
technique known as intarsia). The intarsia workers of	The source of green oak is the Green Stain fungus,
fourteenth and fifteenth century Renaissance Italy were	Chlorociboria aeruginascens, which is common across the
masters at selecting different tree species for their	Northern Hemisphere and Oceania all year round. The
palette of differently colored woods, including a highly	beautiful fruitbodies are infrequently seen, though, so if
prized, but infrequently used verdigris-colored wood	you happen upon rotted wood that has a turquoise coloration
that was utilized when a scene depicted natural scenery	running through it, examine it closely. The tiny stalked
with hills and trees.	cups (sometimes called Green Elf-cups) may be found

on the underside of the wood or within the fissures of

craft of marquetry results in a similar looking finished well-rotted pieces. piece, but is produced by gluing small pieces of wood veneer on to a box, a piece of furniture, or some other surface. One of the most famous examples of marquetry is “Tunbridge ware,” which was produced in and around Royal Tunbridge Wells in Kent, England, from around 1830 to 1900. Like the intarsia workers, the marquetry artisans included the same peculiar blue-green wood, and historians and botanists have long puzzled over the source of this “green oak,” as the Tunbridge artisans referred to it.

However, modern chemical analysis, microscopy, and electron microscopy have given us the answer: the color doesn’t come from the type of tree, but from a fungus that is decomposing it. Fungal growth in wood often causes discoloration, as a result of pigmented hyphae, spores, and

 Closeup of beautiful little fruitbody

changes associated with decomposition of wood, or chemicals

cups of Green Stain fungus,

produced during growth. In general, stained timber is a sign

Chlorociboria aeruginascens.

PATHOGENS, PANDEMICS, &SCOURGES

PATHOGENS, PANDEMICS, & SCOURGES

World-changing fungi

When we think of severe microbial epidemics and pandemics, we mostly think of human pathogens; of bacteria and viruses. However, many of the most devastating pandemics are those that wipe out sources of food. Scientific advances have given us a leg up in this race, but it is only a matter of time before the next microbe strikes.

Globally, fungi are on the march, and despite the best	the most recent and severe die-offs—and extinctions—
efforts of science, destructive fungi have hardly been	ever witnessed in wild species. Many experts now agree
contained. In the first half of the twentieth century,	that fungal infections will cause increasing attrition of
a previously unknown fungus called Cryphonectria	biodiversity, with wider implications for human and
parasiticawas imported to North America with Asian	ecosystem health.
chestnut trees, killing more than 80 percent of the 4	This problem is not exclusive to terrestrial habitats,
billion American chestnut trees. More recent examples	either. The effects of pathogenic fungi are seen in
of trees falling victim to fungi include pines in Canada,	marine environments, where they are most likely
larches in the United Kingdom, and oaks in California.	spurred on by climate change. Worldwide marine corals
	and sea fans are in trouble, and science has slowly been
ALTERED LANDSCAPES	shedding light on the causes of the widespread
Fungal threats to the food supply appear to be on the	“bleaching” and subsequent die-offs. While it was long
rise. Already more crops are lost to fungal diseases than	thought to be a result of increased ultraviolet light or
to viruses, bacteria, and nematodes combined. In the	the warming of the seas, or both, it turns out that
mid-nineteenth century, Late Blight disease of potatoes	infectious diseases may also play a part.
caused the Great Famine (or Irish Potato Famine),	When it comes to sea fans, the culprit is an
while Rice Blast, Wheat Stem Rust, Soybean Rust,	opportunistic fungus—Aspergillus sydowii. This is a
and Corn Smut also threaten some of the world’s most	common terrestrial saprobe, but it now seems to be
important crops. Combined, these fungi destroy enough	involved with sea fan die-offs in the Caribbean as well.
food to feed 600 million people every year, which	We know that given the right conditions the fungus
clearly demonstrates their threat to world food security.	can become a pathogen of plants and vertebrate
To make matters worse, human activity is	animals, but it is not known to sporulate in marine
intensifying fungal disease dispersal, as we modify	water, so the source of aspergillosis in sea fans is
natural environments and create new evolutionary	puzzling. It was initially thought that perhaps spore-
opportunities. Since the year 2000 there has been an	laden soils being carried across the ocean from
increase in the number of virulent infectious diseases in	northern Africa were bringing the fungus, but that
wild animal populations and managed landscapes alike.	notion has since fallen out of favor, leaving scientists
In both plants and animals, an unprecedented number	struggling to find an answer.

of fungal and fungal-like diseases have caused some of

ص Healthy Sea Fan.

س Aspergillusspecies seen under the microscope show conidiophores characteristic of the genus. This structure is reminiscent of an aspergillium, the holy water sprinkler used by Christian priests.

ر Sea Fan showing tissue necrosis as a result of infection with Aspergillus

sydowii.

PATHOGENS, PANDEMICS, & SCOURGES

North America. For many years, herpetologists around

AN AMPHIBIAN KILLER

the world had noticed amphibian populations were in The realm of fungi mostly remains uncharted

decline, but the evidence remained largely anecdotal. territory—we know the names of fewer than 100,000

It was not until the late 1990s that a quantitative different fungi, but DNA sequencing surveys hint at

assessment confirmed negative population trends. between 1.5 million and 5 million species existing in

This pretty much coincided with the identification of total. As an example, the number of known Phytophthora

a previously unknown disease—chytridiomycosis—that species (fungus-like relatives that include the cause of

was causing widespread amphibian mortality in Potato Late Blight) has doubledsince the year 2000.

Australia, as well as North, South, and Central America. Seeing as this was the cause of the Great Famine, which

Thus a fungal pathogen, a member of the phylum killed 1 million people in Ireland alone in the mid

Chytridiomycota (chytrids), came to occupy center 1800s, it is incredible that we do not by now know

stage in the studies of amphibian demise. allthe species in this destructive group.

The causative agent of amphibian chytridiomycosis Fungi are routinely making headlines, and quite is Batrachochytrium dendrobatidis(Bd). The lifecycle of

often the news is not good. Right now we are facing

Bdinvolves a motile, swimming spore that finds a host two major animal crises: a massive decline in amphibian

animal and sticks to its skin; hyphae called rhizoids species, and an explosive disease outbreak among bats in

then grow into the host’s skin and, in a matter of days, a zoosporangium forms that develops new zoospores. The zoospores are eventually released to swim about and further infect the same host or, if they find another amphibian, start a new infection. When most

 Tiny zoosporangium of chytrid

fungus (Batrachochytrium dendrobatidis)

amphibian species reach a Bdthreshold of 10,000

visualized with scanning electron

microscopy.

zoospores covering their skin, they are unable to

breathe, hydrate, osmoregulate (control electrolytes),

 Toad (Alytes muletensis) being

examined for chytridiomycosis disease.

or thermoregulate correctly.

WORLD-CHANGING FUNGI

The facts surrounding this pandemic are not fully	researchers are seeing immunity cropping up in some
known. It is possible that these primitive chytrid fungi	places, and some amphibians are starting to bounce back.
have long been associated with the skin of amphibians	The final chapter in this saga has yet to be written.
and have seemingly lived in harmony until recently.
If this is the case, it may be that global climate change	BAT WHITE-NOSE SYNDROME
and increasing levels of UV sunlight are now stressing	Another fungus seems to have come from out of nowhere
the amphibians and allowing these fungi to become	to afflict a large group of animals. In late winter 2007,
invasive and more pathogenic. Alternatively, this could	researchers found thousands of dead Little Brown Bats
be a brand new pathogen spreading around the globe.	with a white growth on their muzzles and ears in five
There is some evidence for this, as examination of the	caves in upstate NewYork. The following winter, the
skin from preserved amphibians in museum collections	disease showed up in 33 caves, and by early 2012 it had
has found no Bdprior to about 1938, which	spread north to Canada, south into Alabama, and as far
corresponds with the inception of trade in African	west as Missouri. It is currently found in 38 states in the
clawed frogs used in research labs and pet aquaria.	USA and seven Canadian provinces.

What is known is that amphibians are in trouble on a global scale: many species have already gone extinct, and assuredly additional species will as well. Batrachochytrium dendrobatidisis responsible for what is perhaps the largest panzootic (animal pandemic) in history, helped by its extremely broad host range: it has infected 50 percent of frog species (order Anura), 55

 Visible signs of Bat White-nose

percent of salamander and newt species (clade Caudata),

Syndrome on Little Brown Bat (Myotis

lucifugus).

and 29 percent of caecilian species (Gymnophiona).

 False-colored scanning electron

There is some cause for optimism, though. While more

micrograph of Pseudogymnoascus

amphibians will still undoubtedly be wiped out,

destructansfungus.

PATHOGENS, PANDEMICS, & SCOURGES

The disease—Bat White-nose Syndrome (WNS)—	in caves is the ideal habitat. Its propensity to grow on
is caused by Pseudogymnoascus destructans (Pd), formerly	living bats is still somewhat of a mystery, though, and
known as Geomyces destructans. This fungal pathogen is	seems to be opportunistic. Growth on the skin of bats
known to infect at least 13 species of bat, including	seems to irritate them out of hibernation, causing them
several that were already considered endangered. Millions	to fly about earlier than they would usually. This excessive
of bats have been killed and some hibernation sites	activity consumes winter reserves that the bats can ill
(“hibernacula”) have lost their entire population.	afford to lose, and if they leave the cave before spring
According to one study, the Little Brown Bat—one of the	they will waste further energy in the vain search for food.
most common bats in North America—has a greater-	Therefore, the biggest cause of death to bats that succumb
than-99-percent chance of going regionally extinct in the	to WNS is starvation.
East within a decade. Because bats pollinate some plants	The origin of the disease seems to be Europe, where
and eat pest insects, their value to U.S. agriculture has	the fungus is found in caves across the region. However, it
been estimated to be at least $3.7 billion a year.	does not seem to cause any problems for the bats that live
Pseudogymnoascus destructansis a saprobe that is capable	there. This suggests that European bats have been around
of decomposing keratinized materials, as well as chitinous	the fungus for millions of years and have had time to
and cellulosic debris. It seems to do best at cooler	evolve resistance to it. For the bats of North America
temperatures, which explains why organic matter found	there may not be enough time for this to happen.

WORLD-CHANGING FUNGI

CHESTNUT BLIGHT

Staying in North America, it’s likely that no fungus has altered the farmlands and forests there more than Cryphonectria parasitica. Until about 1900, the eastern North American forests were dominated by American Chestnut (Castanea dentata). The tree was so common that it made up close to half of the trees in eastern hardwood forests and much of the ecosystem was tied to the trees in some way. The edible nuts fed the forest wildlife, as well as the region’s Native Americans who relied heavily on the nuts as food through the winter. American Chestnut wood was light, but durable, straight, and with few knots; the heartwood was also decay resistant, making it a favorite with foresters and woodworkers. The tree grew quickly, too, regenerating easily from the sprouts arising from cut stumps. As plant pathologist Alan Biggs put it: “The tree served humankind from the cradle to the grave, often supplying the wood for both the cradle and the casket.”

That all changed in 1904—the year that Chestnut

Blight arrived in North America. Cryphonectria(Endothia)	several years in the forest understory, until they reach a few
parasiticawas introduced into the NewYork City area,	inches in diameter, although the fungus kills most of them
hidden among a load of Japanese Chestnut trees. It didn’t	before they become mature enough to produce nuts.
stay put. Spreading by about 50 miles a year, the disease	This story could still have a happy ending, though.
had wiped out enough trees by 1913 that it warranted	Following a 30-year effort to restore American Chestnut,
investigation by the USDA. Unlike Japanese and Chinese	there are now signs of success. Researchers are deploying a
varieties of chestnut, American Chestnut was not resistant	three-pronged attack using hypovirulence, traditional
to the disease, and by 1940 more than 3.5 billiontrees had	backcross breeding and hybridization, and genetic
been killed by the fungus.	engineering. Hypovirulence is a type of biological control
In less than 50 years after its introduction into North	that exploits a naturally occurring virus parasite of
America, C. parasiticavirtually eliminated American	Cryphonectria. Once the fungus is infected, it is less virulent
Chestnut as a canopy species and changed forever the	as a pathogen of trees; hypovirulence slows the expansion
forest makeup.Yet despite this, American Chestnut	of the canker, allowing the tree to wall off the infection.
continues to survive via root sprouts, as the fungus does	Researchers can culture the virus parasite in the lab and
not go below the soil line. These sprouts often survive for	spray it over trees, essentially sickening the fungus to keep

the trees healthy.

Additionally, researchers have been crossing susceptible American Chestnut trees with resistant varieties of Japanese and Chinese trees, as well as using molecular biology to insert genes for resistance into susceptible lines. Resistant varieties of American Chestnut

ر American Chestnut (Castanea

dentata) in bloom.

have now been developed and are awaiting approval for

release to the public and to the forests after being absent

ض Visible signs of Chestnut Blight on

the bark of a chestnut tree in Adams

for more than a century.

County, Ohio, USA.

PATHOGENS, PANDEMICS, & SCOURGES

DUTCH ELM DISEASE	tree’s death, the fungus goes into sexual reproduction
Although there is reason to be optimistic about the	mode, producing fruitbodies (many, many fruitbodies if
American Chestnut, this is not the only tree to have	you’re lucky!) and starting the circle of life all over again,
suffered over the past century. Every spring a mycological	presumably with elm seedlings in the vicinity. Assuming
rite plays out, with mycophiles heading to the woods in	favorable conditions, the fruiting will be most abundant
a much-anticipated search for wild morel mushrooms.	in the first year after the tree’s death; fruiting may occur
Throughout eastern North America the search will	a second and subsequent year, but always tapers way off
focus on habitats with elm trees, because while the	and ends altogether shortly thereafter.
life cycle is still not entirely understood, it seems that	I learned about the elm-morel connection as a kid
some species of yellow morel (Morchellaspp.) have a	growing up in the American Midwest—my family was
mycorrhizal association with those trees. Upon the host	passionate about picking morels, as was just about

everyone we knew! But while I’ve always loved elm trees for their ties to morels, my affection has always been even stronger for their beauty. This is especially so for the American Elm (Ulmus americana). It’s not just me, either. For a long time, this tree was thechoice of

س Severe damage caused by bark

urban planners and urban foresters; its perfect form,

beetles; the insects are the vector of

Dutch Elm Disease.

heavy shading foliage, very high spreading canopy, and

WORLD-CHANGING FUNGI

WOMEN PIONEERS OF MYCOLOGY

It is now pretty certain that the disease originated in Asia, but a century ago no one was sure what it was or where it came from. All manner of infectious agents were blamed, ranging from a bacterium to the weather, and even poisonous gases used in World War One. In 1921 the mystery of elm tree death was solved in the laboratory run by the Dutch plant pathologist Johanna Westerdijk. The fungus—an ascomycete—was identified by one of Westerdijk’s grad students, Marie Beatrice “Bea” Schwarz, who grew a mold out of infected wood, inoculated it into a healthy tree, and found that it quickly caused symptoms of the disease in that tree, followed rapidly by death. The re-isolated fungus was an asexual mold that Schwarz dubbed Graphium ulmiin 1922; the sexual stage was later discovered and named Ceratostomella ulmiby Christine Buisman, also of Westerdijk’s lab (the fungus was later named Ceratocystis ulmi, and today goes by Ophiostoma ulmi).

lack of messiness (they do not shed large fruits and	Dutch Elm Disease is now very common in North
are not prone to dropping branches) made it the ideal	America, where it is considered the most destructive
street tree for cities in the East and elsewhere. So cities	shade tree disease. Sexual reproduction is rare, though,
became full of American Elm trees; streets were lined	so most infections are believed to be caused by the
with them, and city parks and college campuses were	asexual form of the fungus, which has a fascinating life
forested with them.	cycle involving an obligate insect partner. There are
However, in the early 1900s a strange disease started	several species of bark beetle that transmit Ophiostoma
killing species of elm in Europe and it was not long	to elm trees, and these beetles are only attracted to trees
before the same thing was happening in North America.	that are of reproductive age and have thick phloem
Elm death was first noted in Cleveland, Ohio, and then	(the nutrient-transporting vascular tissue). Trees that are
in Cincinnati shortly thereafter. The disease spread	weakened from the fungus or other stressors may show
swiftly, and wherever it turned up, death to elm trees	signs by “flagging,” whereby one or more branches
was certain. Most species of Ulmus, and the closely	shows yellowing leaves. A weakened tree becomes the
related Zelkova, are sensitive; in North America the	focus of further attack by other beetles, at which point
lovely Ulmus americanamay be the most sensitive of all.	the fate of the tree is all but sealed.

WORLD-CHANGING FUNGI

However, as with American Chestnut trees, elm	The cause of SOD is an oomycete, Phytophthora
breeders have been hard at work to cross wild specimens	ramorum, and despite a quarantine in 2001, SOD has
that show some resistance, in the hopes of creating fully	spread up the West Coast and moved into British
resistant progeny. They are having some success—a	Columbia. States across the USA have imposed bans
variety of cultivated elm (Ulmus minor“Christine	on all nursery stock from California, but every two or
Buisman”) that is resistant to Dutch Elm Disease was	three years infected material escapes quarantine—the
recently made available to the public, and with it, the	most egregious escape involved a major nationwide
hope that someday big old elms may once again grace	nursery supplier and resulted in contaminated nursery
forests and cityscapes.	stock being shipped to hundreds of nurseries across
	states. Many now fear the pathogen could spread
EMERGING THREATS	to forests in the Southeast and elsewhere, causing
While progress is being made in combatting Chestnut	untold destruction.
Blight and Dutch Elm Disease, a pair of emerging tree	About the same time that SOD was being
diseases are now causing alarm and have researchers	discovered on North America’s West Coast, another
searching for solutions. Sudden Oak Death (SOD)	amazing discovery was being made on the opposite side
causes a lethal infection of the trunks of several species	of the planet. In 1994, David Noble, an officer with the
of oak and has killed hundreds of thousands of trees	New South Wales National Parks and Wildlife Service,
since it turned up in California in 1995; Tanbark Oak	rappelled into a narrow canyon in Wollemi National
die-offs were noticed first, then Coast Live Oak started	Park in southwest Australia. There, he came across a
to die as well. The pathogen is a problem in Europe as	grove of large trees that he didn’t recognize.
well, and sickens several other unrelated species including	Noble collected a few twigs and showed them to
azaleas, Rhododendron, Viburnum, larch, and maples.	biologists and botanists who were similarly stumped.

ص One of the oldest known elm trees, a 400-year-old specimen in Preston Park, Brighton (UK) felled by Dutch Elm Disease.

ز Saprobic fungi soon colonize trees killed by SOD; these black fruiting bodies are of Annulohypoxylon thouarsianumon Tanbark Oak (Lithocarpus densiflorus).

PATHOGENS, PANDEMICS, AND SCOURGES

WORLD-CHANGING FUNGI

Investigators soon realized that these specimens were

ر Wollemi Pine (Wollemia nobilis)

growing at Kew Gardens, London.

not only an unknown species, but also a tree outside

any existing genus of the ancient Araucariaceae family

ش Larch trees (Larix decidua)

near Hawkshead, Lake District (UK)

of conifers. It’s hard to believe something so large could

infected with SOD; cut stems showing

“bleeding” which is a tell-tale sign

go unnoticed, as some of the trees are between 90 and

of the disease.

feet (27-40m) tall, but a new genus—Wollemia— was created to contain the strange trees.

The Wollemi Pines may be the rarest trees on the planet, as to date only a single grove of 200 specimens has been found, contained in a narrow canyon less than 120 miles (195km) west of Sydney. It appears that the special characteristics of the tree’s habitat have played a major part in facilitating its survival in such small groves. Hidden in narrow sandstone ravines, the Wollemi Pine enjoys consistent humidity and moist soils, which suit both the plant and the mycorrhizal fungi that live in association with its roots. Like almost

PATHOGENS, PANDEMICS, AND SCOURGES

Hidden in plain sight

Map of New South Wales. The Wollemi Pine had gone undiscovered since the beginning of time, despite being just a few hours’ drive from major urban centers.

New South Wales

Wollemi

National Park

Australia

Sydney

Wollemi

National Park

CLOSE CALL

On 16 January 2020, firefighters saved the last Wollemi Pines left in the wild from the Gospers Mountain fire. Known as a “mega fire,” the fire went on to destroy an area across Australia seven

Wollemi Pines

times the size of Singapore.

contained in a

canyon

The Wollemi Pine is sometimes called a “Lazarus taxon.” Like Lazarus, whom Jesus brought back from the dead in the Bible, these trees were thought to be extinct, but then a few surviving members were discovered.

One of the Wollemi Pine’s closest living relatives is the Monkey Puzzle Tree (Araucaria araucana).

The Duke of Edinburgh planted one of two Wollemi Pines near the Orangery at Kew Gardens in England for its 250th anniversary in 2009.

WORLD-CHANGING FUNGI

all Australian plants, Wollemia nobilisdepends heavily on	also been cultivated successfully and is now found in
a symbiotic fungus to penetrate the hard ground and	some botanical gardens around the world, as well as
take up nutrients from the continent’s notoriously	occasionally being sold as seedlings to homeowners,
infertile soils. However, unlike other fungi, those that	joining the Dawn Redwood and Ginkgo bilobaas a
coexist with the Wollemi Pine are unlikely to thrive in	horticultural “living fossil.”

the thin, drier soils of the surrounding plateaus. So, in a sense, both organisms may depend entirely on the other for survival.

Yet no sooner was it discovered, than Wollemia was threatened with extinction. Caretakers noticed some of the trees were beginning to die, and researchers quickly determined that Phytophthora cinnamomi—a close relative to the causal fungi of SOD in North America—was the culprit. Thankfully, the disease outbreak was treated successfully, and anyone authorized to visit the Wollemi Pine grove must now undergo strict infection control procedures that involve

س Phytophthora cinnamomiviewed

sterilizing their footwear and equipment. Wollemiahas

under microscopy.

PATHOGENS, PANDEMICS, & SCOURGES

Fungi through history

While it’s clear that fungi have altered the landscape, they have also changed the course of history. Possibly the most famous assassination-by-fungus (or at least the most-told) was the murder of Claudius Caesar, but other world leaders have also been felled.

The rule of Pope Clement VII (1478-1534) is notable in the annals of history, not so much for its duration, but for the world upheaval that happened during his reign, which included The Reformation and the Sack of Rome. Clement VII’s papacy ended (along with his life) in 1534, and was attributed to him eating Death Cap mushrooms (Amanita phalloides). However, most historians now dismiss this theory as he suffered for several months before succumbing—Death Caps kill far quicker.Yet while a fungus may not have killed Clement VII, it does seem likely that the Holy Roman Emperor, Charles VI (1685-1740), died after eating a meal of Death Caps while on a hunting trip in the Austrian mountains. Charles VI led a lavish lifestyle, and neither the royal family, nor his financial advisors, nor his loyal subjects could stop him. In the end, though, the mighty mushroom did.

While the Death Cap might have have been implicated in the deaths of both a pope and a king, arguably the most infamous ascomycete is the ergot fungus Claviceps purpurea. Widespread across North America and Europe, it contains a toxic alkaloid compound closely related to LSD and capable of causing strong hallucinations. Such is its potency that some historians believe the Salem witch trials in the late 1600s, which saw more than 200 people accused of witchcraft and 19 executed, were a result of ergotism, and that the Great Fear at the start of the French revolution may also have resulted from Ergot poisoning.

FUNGI THROUGH HISTORY

ش Fungi on trial? The Witch, No. 1,	ز The cause of ergotism, Claviceps
by Joseph E. Baker (ca. 1837-1914).	purpureagrowing on cereal grain.

PATHOGENS, PANDEMICS, & SCOURGES

A TASTE FOR COFFEE

Why do the British drink tea? It’s so much a part of that culture that you would assume it has always been that way. But you would be wrong. The British used to be coffee lovers, and like most of the world, once got its coffee from huge plantations in India and Sri Lanka (formerly Ceylon). At least that was the case until Coffee Rust arrived. First diagnosed in Ceylon, it wasn’t long before the rust meant that coffee plants could no longer be cultivated in the region profitably, and so the British decided that tea was a suitable replacement.

At that time, the New World had never seen coffee plants (or Coffee Rust), so Central and South America became the center of coffee cultivation. Yet despite the best efforts, Coffee Rust was on its way, jumping from Ceylon and India to other countries in Asia and Africa, before leaping the Atlantic to Brazil in the 1950s, and reaching Nicaragua in 1976. By 1981, la roya, as it’s known in Spanish, had spread north to Mexico, and south across the large coffee producers in South America.

Today, most of the world’s coffee beans come from South and Central America—Brazil is the world’s largest producer by far. Coffee production is so economically important to the region that this tiny fungus could devastate some nations, and put the livelihoods of millions of people at stake. But even though there is so much at stake, much of the lifestyle of the Coffee Rust fungus (Hemileia vastatrix) is still entirely unknown. What we do know, though, is that Coffee Rust fungus is so widespread that there is likely no way that it could ever be eradicated. The best we can hope for is that a combination of modern research

techniques and old-fashioned cultivation practices can

ص Coffee beans ripening on a

bring it under control.

Coffea arabicaTree.

ر Coffee plantation near Manizales in the Coffee Triangle of Colombia.

س س Coffee bushes being fumigated to stave off infection by Coffee Rust in Guatemala (top).

س Coffee leaf showing symptoms of infection by Hemileia vastatrix(inset).

PATHOGENS, PANDEMICS, & SCOURGES

Human impact

There have been episodes in our past where millions of human lives have been lost due to fungi and fungi-like pathogens wiping out crop plants and causing mass starvation. Probably the most infamous is the Great Famine, which hit Europe in the mid 1800s.

The cause of Late Blight disease in potatoes is an	remaining in plant residue, or a single tiny tuber left
oomycete “fungus.” Long considered fungi, due to a	over from the previous crop, and the disease can sweep
similarity in appearance, oomycetes (or water molds)	through an entire crop with amazing speed; if the
are now treated as a distinct lineage of fungus-like	conditions are cool and wet, the pathogen can destroy
Eukaryotes that are related to organisms such as brown	an entire field in as little as one week. Even if the losses
algae and diatoms. The most destructive pathogen of	in the field are minimal, tubers can still become
potato is Phytophthora infestans, which is part of the	infected during harvest and rot in storage.
“plant destroyer” genus Phytophthora, one of the most	Hyphae emerge from infected plants and produce
important groups of plant pathogens in history.	spores that are spread by wind, or zoospores (depending
Late Blight disease is still around today—indeed, it	on temperatures) that can swim through damp soil and
is coming back with renewed vigor, and afflicts tomato	infect tubers. In either case, these spores will germinate
plants as well. All it takes is a single spore or hyphae	and infect the plant, growing throughout the host tissue

MICROBIAL MURRAIN

The Great Famine hit Ireland hardest (hence its alternative name, the Irish Potato Famine), with 1 million people starving to death in the space of just a few years, and another 2 million or more fleeing the country. The country’s population has never rebounded fully from these losses, and is still far lower than it was prior to the famine; the island of Ireland’s current population is around 6.7 million people, compared to a pre-famine figure of roughly 8.5 million.

HUMAN IMPACT

Disease cycle of Late Blight

Infection spreads quickly via motile zoospores. All parts of the potato plant may be infected. If two mating types are present, sexual reproduction can occur; oogonia (female) and antheridia (male) structures fuse to create oospores.

Sporangium

Zoospores Sporangium

Zoospores enter plant tissues

Infected leaf

Seedling produced by infected tuber becomes infected

Oospore

Oogonium

Infected foliage

Infected tubers Antheridium

KEY

Sexual phase

Asexual phase

PATHOGENS, PANDEMICS, & SCOURGES

(HERB-1)

Early 1900s

(US-1)

Early 1800s

P. infestansorigin

Potato origin

Pathogen spread

Initially, a single mating type of the Late Blight pathogen found its way to potatoes. Much later, an invasion by a second mating type has led to sexual reproduction and increased genetic diversity for this destructive organism.

and emerging from the stomata to produce additional	pretty well established as the center of origin for the
sporangiophores. Infected plants will be a source of	pathogen, while the center of origin for the potato is
additional infectious spores after roughly four days,	in the Andes Mountains.
ensuring a tremendous number of asexual generations	The indigenous peoples of the Andes have grown
are possible in a single growing season.	the crop for centuries, probably relatively disease free.
Luckily for the world, this organism was not known	This is where potatoes were discovered by Europeans,
to undergo sexual reproduction. As a result, scientists	who took them back to the Old World where they
started to get the upper hand through the development	quickly became a popular food source. At this time the
of fungicides, as well as classic plant breeding techniques	potatoes were free from Late Blight, as the pathogen
that produced several potato cultivars that were resistant	wasn’t present in Europe. However, this was set to
to Late Blight. However, that all came to an end in the	change when Europeans started to immigrate to North
s when—from nowhere—the pathogen swiftly	America.
became immune to fungicides and broke through the	In the New World, Phytophthora infestanswas a
resistant potato varieties. A second mating type had	pathogen of native solanceous plants (peppers, tomatoes,
found its way to the world’s potato fields.	and eggplants), and it could also infect the potatoes
It turns out that the lifecycle of Phytophthora	being bought across from Europe. As trade increased
infestansdoes involve sexual reproduction, but until the	between Europeans in the New World and those in the
s it had rarely been seen and was hardly known. To	Old, the Late Blight pathogen made the jump between
learn about this newly evolving threat, scientists had to	the two continents, in the form of the A1 strain.
back up and take a look at the evolutionary history of	This strain was active for decades, but while it was
the pathogen. Based on the amount of genetic diversity	destructive it only reproduced asexually. However, in
within the species in central Mexico, as well as a	the 1980s a second mating type (A2) found its way to
number of other closely related species, this area is	Europe, and to North America soon thereafter. This

HUMAN IMPACT

ر Phytophthora infestanswas long thought to be a true fungus because it grows as hyphae.

ش Early illustration of Late Blight of potato (1888).

enabled sexual reproduction to occur, and with that came genetic recombination, leading to the very real possibility that we could once again face the complete destruction of potato crops.

This makes potatoes something of a conundrum. Worldwide, potatoes are the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world’s population. In North America they are one of the cheapest food items you can buy, but paradoxically they are one of the most expensive crops to grow, as they require a tremendous amount of chemical applications to keep numerous pathogens at bay. Among these is Phytophthora infestans—a virulent pathogen just waiting for a host. Each year the weather dictates how benign or severe the outbreak of Late Blight will be, but it is currently estimated that the annual worldwide cost of potato crop losses due to Late Blight is around US$7 billion. This explains why potato growers monitor the weather, getting minuteby-minute updates on conditions conducive for an outbreak, and try to prophylactically apply fungicides at the first sign of infection.

PATHOGENS, PANDEMICS, & SCOURGES

AMANITA CAESAREA

Caesar’s Mushroom

	SCIENTIFIC NAME	Amanita caesarea
History maker	PHYLUM	Basidiomycota
	ORDER	Agaricales
	FAMILY	Amanitaceae
	HABITAT	Forest

Possibly the most infamous of all murders attributed	repeatedly argued with Claudius to make her son, Nero,
to poisonous mushrooms—and one that may have	next in line to the throne, but Claudius favored his own son
changed the course of world history—involves the	by blood, Britannicus. It’s also clear that following the murder,
death of the Roman ruler, Claudius Caesar, in AD 54.	Nero did become the Roman ruler—and we know how that
Presumably it was his fondness for ovulithat led to the	turned out.
highly prized edible Amanitas being named Caesar’s	Much has been written about Claudius’s death and
Mushroom. It also led to his death.	scholars disagree as to exactly what the poison was, how it
	was administered, and who slipped it into his meal. I guess
Claudius Caesar ascended the throne following the	you could say that Claudius died de una uxore nimia, or “of
assassination of his nephew, Caligula. At the time, Caligula	one too many wives!” It is also worth pointing out that to
had been permitting the older Claudius to sort of jointly rule,	this day there are many popular Italian dishes named for
but this was mostly so he had Claudius around to serve as a	Caesar, but none for Agrippina.

scapegoat when things went wrong, or for public humiliation, to the benefit of Caligula. With Caligula out of the picture, Claudius became sole emperor and most historians remember him favorably. If he had any flaws it was that he was a womanizer—during his reign, Claudius had four wives, or six if you count the one who died mysteriously on their wedding night, and another betrothal that ended at the altar when family members interceded.

Claudius’s fourth wife was Agrippina, a relative of Augustus, and in fact Claudius’s niece. Claudius made Agrippina’s son, Nero, his own adopted son. Most scholars have written that the marriage was one of convenience and politically motivated, but even so, it lasted for many years, until the untimely death of Claudius. By all accounts

Claudius was poisoned with his favorite dish of mushrooms,

 Caesar’s Mushrooms are found

throughout the Northern Hemisphere.

but whether toxic Amanitas were mixed in with edible ones

The beautiful European species,

will never be known. What is clear is that Agrippina had

Amanita caesarea, is seen here.

PATHOGENS, PANDEMICS, & SCOURGES

SPOROPHAGOMYCES CHRYSOSTOMUS

Spore Eater

	SCIENTIFIC NAME	Sporophagomyces chrysostomus
Unusual lifestyle	PHYLUM	Ascomycota
	ORDER	Hypocreales
	FAMILY	Hypocreaceae
	HABITAT	Forest

Shelf fungi don’t often look like much, but they can	imagine that this is an unusual lifestyle for a fungus, and
have interesting physiologies. Many are also perennial,	it was this strange habit (along with some other unique
persisting on their woody hosts year round, so you can	features) that led Finnish mycologist Kadri Pُldmaa to
observe them in the middle of winter. So the next time	suspect that three species of spore eaters should not be
you encounter a shelf fungus, take a close look—	taxonomically sorted with all the other species of Hypomyces
sometimes what appears to be a moldy old polypore	(a large group of mycoparasitic fungi). DNA sequence
is neither old, nor moldy.	analysis supported her conclusions that a new genus was
	needed to contain the three species, and so Sporophagomyces
To the casual observer, Sporophagomyces chrysostomusappears	was christened in 1999.
to be a dirty whitish to brownish mold growing on the	Sporophagomyces chrysostomusis found all over the world
underside of Artist’s Conk or other woody polypores. But this	and is most often associated with Ganodermaspecies of shelf
fungus is probably neither a saprobe, nor a parasite—as the	fungi. The hyphae of S. chrysostomusgrow just beneath the
name implies, Sporophagomycesis an eater of spores. You might	underside of the polypores, where they catch the numerous
	spores that rain down; this strange fungus then pierces the
	spore cell walls and feeds on the contents. Other than that,
Eating light	not much else is known about its biology. It’s likely that when
Sporophagomycesfungus	specimens of Ganodermaare collected, Sporophagomycesmight

has the curious habit of

living off of the spores of

be considered debris or contaminants and removed prior to

other fungi. Fungal spores

preservation. In rare cases where Sporophagomyceshas been

are extremely small; the

spores of this featured

purposely collected, its host has often not been kept,

fungus are shown and

measure less than 20 μm

rendering the collection incomplete and less informative.

(1 μm is 1/1,000,000th of a meter).

 Sporophagomyces chrysostomus

growing over the hymenial (underside)

μm	surface of a polypore.

PATHOGENS, PANDEMICS, & SCOURGES

PLASMOPARA VITICOLA

Downy Mildew

	SCIENTIFIC NAME	Plasmopara viticola
	PHYLUM	Oomycota
	ORDER	Peronosporales
of Grape
	FAMILY	Peronosporaceae
	HABITAT	Vineyards
Scientific serendipity

Some of the greatest scientific discoveries can be	closest to the road were splashed with a strange blue-green
chalked up to serendipity—being in the right place at	substance. His curiosity piqued, he began to inspect the plants
the right time—but more often, the discovery relies on	and noticed that wherever the blue-green substance had been
a keen mind and astute observation. It was just such	applied, the leaves were completely free of Downy Mildew.
an astute observation that led to a discovery that saved	The grower revealed that a mixture of copper sulfate and
the French wine industry in the late nineteenth century.	lime had been applied to the plants to discourage pilferers
At that time, a disease called Downy Mildew of Grape	from picking his grapes. Millardet found this “Bordeaux
plagued vineyards in France.	Mixture” worked well against all manner of fungi, and a
	century-and-a-half later, Bordeaux Mixture remains one
The disease was caused by an oomycete “fungus” called	of the most-used fungicides.
Plasmopara viticola, which has a standard oomycete lifecycle.
Oospores (sexual spores) overwinter within the fallen leaves
of the previous year and in the spring they germinate to	Wine thief
produce sporangia (receptacles that form asexual spores) and	Plasmopara viticolais very destructive

to wine grapes. Disease-causing spores are

motile zoospores. These are both carried to living plant tissue produced in tremendous numbers from tiny tree-like sporangia. Measurements are shown

by wind or splashed by rainfall. Motile by way of flagella,

(1 μm is 1/1,000,000th of a meter).

zoospores are capable of swimming over the leaf surface to find an infection site, and infection spreads swiftly within the plant tissue. New sporangiophores emerge within a few days, producing more spores that can further spread the disease. At the end of the growing season, all that remains are bare plants and plenty of dormant oospores.

In 1876 a brilliant French botanist, Pierre Marie Alexis Millardet, took up a professorship position at the University of Bordeaux. Millardet was studying a recent outbreak of disease caused by an insect, Phylloxera, which afflicted the roots of grapevines, but this coincided with Downy Mildew of Grape decimating vines. One day, while strolling home

	μm	 Healthy and withered grapes
past local vineyards, Millardet noticed that the grape vines		showing signs of Downey Mildew.

PATHOGENS, PANDEMICS, & SCOURGES

CRYPTOCOCCUS GATTII

Emerging Threat

	SCIENTIFIC NAME	Cryptococcus gattii
Human pathogen	PHYLUM	Basidiomycota
	ORDER	Tremellales
	FAMILY	Tremellaceae
	HABITAT	Forest

Exotic pathogens can seemingly come out of nowhere	earthquake ever recorded in the Northern Hemisphere,
to strike. Since the 1990s a mysterious fungal pathogen	and the tsunami it spawned inundated the entire West
has been spreading slowly through the Pacific Northwest,	Coast, most likely carrying Cryptococcusinland with it.
where it has sickened or killed hundreds of people;	Experts feel it has taken about three decades for this
victims often contract this fungus simply from a stroll	fungus to adapt to life outside of its home in the tropics, and
in the woods. Researchers determined the culprit was	during that time it has become a more virulent pathogen.
Cryptococcus gattii, a fungus known to cause rare but	Cryptococcosis—the disease it causes—is contracted when
potentially severe brain and lung infections, and death.	virulent forms of C. gattiiare inhaled. The fungus is engulfed
	by the human immune system, but resists destruction. Instead,
Although Cryptococcus gattiihas a global distribution, it is	it uses the body’s infection-busting cells (macrophages) as
normally restricted to tropical regions, so how this fungus got	a sort of Trojan horse to spread via the bloodstream. It is
to the Pacific Northwest was puzzling. However, researchers	thought that the fungus evolved this trick as a way of
now think they have the answer, which involves one of the	avoiding digestion by amoebae in soil environments.

most unlikely series of events in the annals of mycology. Based on genetic analysis of all the samples taken from patients, as well as environmental collections, it is now known that virulent forms of C. gattiiarrived during three different episodes over an 88-year-period. All three strains seem to have originated from eastern South America, with the arrival of the first strain correlating with the opening of the Panama Canal in 1914. It is thought that the fungus—which can live in seawater for up to a year—was transported in the ballast of ocean-going ships, and that this same process then happened on two further occasions.

As all three strains of the fungus are found throughout marine environments, something must have happened during the past few decades to drive this fungus further inland, and

 Microscopic image of single-celled

researchers have now pinpointed an incredibly random event:

fungus Cryptococcus gattiitaken from

the Great Alaskan Earthquake of 1964. This was the largest

biopsy; fungal cells stained pink.

PATHOGENS, PANDEMICS, & SCOURGES

CALOCYBE GAMBOSA

St. George’s

	SCIENTIFIC NAME	Calocybe gambosa
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Mushroom
	FAMILY	Lyophyllaceae
	HABITAT	Grassland
Celebrated mushroom

Calocybe gambosa(also known as Tricholoma	As for the saint it was named after, St. George is
gambosa) gets its common name from the fact that it	celebrated as a vanquisher of scourges and slayer of dragons.
fruits reliably on or around the Feast of St. George,	Historians believe there was a figure called George who was
April 23. However, as global climate change causes	a prominent Christian in the reign of the pagan Roman
mushrooms to fruit earlier it may soon develop well	Emperor, Diocletian. One version of his life records that he
before this date, causing future generations to wonder	was an officer who publicly proclaimed himself a Christian
why it was given the name at all.	at a time when the emperor was an atheist, for which he was
	swiftly tortured and beheaded in 303 AD. Many images of the
As best as anyone can tell, this mushroom is not present in	martyr St. George depict him slaying a dragon—we can either
North America, but due to its tremendous popularity in	presume that he slayed the last one, as they’ve not been seen
Europe, many people in the New World have heard of it.	since, or, more likely, that the dragon is a metaphorical depiction
This popular edible fruits from grassy areas and parks, where	of evil or atheism. In either case, if you’re in Europe on this
it forms large, highly visible fairy rings—some of the largest	year’s Feast of St. George, be on the lookout for St. George’s
rings are thought to have been around for several centuries.	flags a-flying and St. George’s mushrooms a-popping.

 St. George’s Mushroom, Calocybe gambosa.

PATHOGENS, PANDEMICS, & SCOURGES

NECTRIOPSIS VIOLACEA

Slime Mold Eater

	SCIENTIFIC NAME	Nectriopsis violacea
Cryptic fungus	PHYLUM	Ascomycota
	ORDER	Hypocreales
	FAMILY	Bionectriaceae
	HABITAT	Forest and urban

Slime molds (myxomycetes) are an interesting group	In fact, we now know that Fuligo septicavar. violaceais not
of amoeboid organisms that confounded scientists for	entirely a slime mold—the violet color (which can be quite
centuries. Without doubt you’ve seen them, but maybe	vivid or faded to gray) is actually a parasitic fungus. The
had no idea what they are, as they move about their	fungus in question is Nectriopsis violacea, which has the curious
environment, oozing over surfaces, gobbling up	habit of dining on the sporangia of slime molds. Nectriopsis
bacteria and other microbes. Given the morphology	violacea(and closely related species) are widely distributed in
and growth habits of many of them, they were long	North America and Europe, as well as the tropics. They are
thought to be fungi, but with the help of modern	especially common on Fuligo septicain bogs, where this
molecular tools, scientists have now placed them	species grows over the tips of gametophytes of Sphagnum.
among the protozoans—not quite fungal and not	Although rarely noted, it’s actually quite common if you
quite animal.	know what you are seeing, so next time you encounter a

slime mold, take a closer look—there may be more to it

the best known of all slime molds is Fuligo septica, than meets the eye. the delightfully named Dog Vomit Slime Mold. This hefty plasmodium is known globally, and is just as common in urban habitats as it is in natural areas, if not more so. Throw down some fresh wood mulch, douse with water, and in a day or two you’ll note the appearance of large amorphous masses that look like piles of bright yellow scrambled eggs; the yellow can fade to a peach color, but often turns shades of gray or even violet. The great mycologist Elias Magnus Fries named the species and several “varieties” based on their color variants, but it’s now thought that Fries may have goofed when thinking different colors meant different varieties.

 Beautiful purple fungus Nectriopsis

violaceaconsuming a large slime mold.

MUTUALISTIC

SYMBIONTS

MUTUALISTIC SYMBIONTS

Everything depends on everything else

Symbiosis is all about the relationships between different organisms. But as you will see in this chapter, these relationships are often far from straightforward, and certainly not always harmonious.

The term “symbiosis” was first coined in the nineteenth	associations can become parasitic, for example,
century to describe lichens, which are organisms	and the partners may no longer get along.
composed of fungal and photosynthetic partners	Symbioses can be obligate, meaning that the
(usually a cyanobacterium or an alga, or both), living	relationship is essential for the survival of one or both
intimately together. Because of this, people often	partners, or they can be non-obligate. In the case of
confuse symbiosis with “mutualism.” This is not to say	viruses the symbiosis is always obligate, as they cannot
that a symbiotic relationship can’t involve two (or	replicate outside their host. However, while they are
more) partners living in harmony, but their relationship	often thought of as purely antagonistic, examples of
can just as easily be antagonistic or commensal. A	mutualistic viruses have been described for several
symbiotic relationship can also belong to more than	decades; there are viruses that reduce the effect of
one of these categories, varying with the environment	diseases caused by other viruses or other pathogens
or other circumstances; under stress, mutualistic	or benefit their hosts because they kill competitors.

ر The symbiosis between ants and fungi have long fascinated us. This image is of fungus garden with eggs from a 1906 edition of Popular Sciencemagazine.

ز Attine, or leafcutter ants don’t actually live on the plant matter they harvest, instead they cultivate lush fungal gardens underground on which they subsist.

MUTUALISTIC SYMBIONTS

Fungus-animal mutualisms

There are countless examples of fungi and insects benefiting one another through random acts, such as an insect inadvertently carrying spores to a host substrate. But there are also far deeper and more deliberate relationships that have evolved over time.

The great evolutionary ecologist Dan Janzen	advantageous to the parasite if it does less harm to its
considered coevolution to be “an evolutionary change	host; if it can take this a step further and be of some
in a trait or traits of one organism, as a response to	benefit to its host then it can increase its own fitness
traits of another, different, species of organism.” As an	even further. In this way (and after long periods of
example, symbioses that may have begun as parasitism	coevolution) some species can become completely
or predation can see the organisms coevolve into a	reliant upon another for survival.

more benign relationship. Indeed, it is often

FUNGUS-ANIMAL MUTUALISMS

DOWN ON THE FARM	our own commercial agricultural practices. At a
I come from a long line of farmers and have cultivated	commercial scale we often find a partitioning of labor,
more kinds of plants than I can remember, and some	with people devoted to the single tasks of cultivation,
types of edible mushrooms. We are not the only	planting, or harvesting. In ant and termite farmers a
organisms who farm other organisms, though. There	similar thing happens, with different castes specialized
are extensively studied mutualisms including fungus-	to one main task, while Ambrosia Beetle (Xyleborinus
farming ants and termites, as well as ambrosia beetles,	saxesenii) mutualisms see a division of labor between
and others are being discovered.	larval and adult colony members.
Among the defining features of human agriculture	Several species of New World ants collect plant
are habitual planting (the tilling of the soil and seeding,	material and use it to cultivate species of the
or “inoculation”); cultivation (“weeding” and the	basidiomycete fungi tribe Leucocoprineae (family
removal of pests and disease); harvesting; and nutritional	Agaricaceae). Attine ants are a group of fungus-farming
dependency. Amazingly, insect farmers exhibit the same	ants originating in South America. These so-called
characteristics. Their farming strategies include evolved	social insect farmers cultivate fungi in subterranean
mechanisms for substrate preparation, inoculation with	gardens, using a process of decomposition rather than
crop propagules, optimization of fungal growth through	photosynthesis to produce and harvest the nutrients
regular activities, protection of the crop against parasites	they need to survive.
or diseases, harvest, and consumption of fungi. There	DNA analysis of the genome sequences of seven
are further parallels between some insect farmers and	ant species and their corresponding fungi partners

Environmental engineers
	Worker ants need	Ants build porous
At first glance, busy ants appear	quick access so there	turrets above ground
to come and go from a big pile of	are often several entry	that help ventilate
dirt. A close inspection reveals a	and exit points	the nest

sophisticated structure with zones for rearing young and cultivating food.

The fungus is cultured

in garden chambers underground

ر Leafcutter ants (Attussp.) tending their fungus garden.

MUTUALISTIC SYMBIONTS

Form follows function

Perforatorium

Termitomycesfungi are cultivated in termite nests buried deeply in soil. As the stem elongates, the cap is pushed toward the soil surface. The mushroom cap will not fully expand and begin sporulation until it has emerged from the soil.

Stalk

Soil

Pseudorhiza

Termite

Fungal garden

Termite nest

SOLO FLIGHT

Most termites start their fungal gardens from scratch when they begin a new colony. They collect spores from fruitbodies to begin their new crop, but only a few termite species take their fungus with them when they emerge to start a new life. Madagascar has proved intriguing to naturalists due to its rich and unique flora and fauna. The island has been isolated for millions of years, and the big question is: how did organisms get there? One suggestion is that rafts full of animals and plants floated over the ocean from Africa; another is that the lighter animals, seeds, and fungal spores may have travelled with the air currents in the atmosphere. The termites that grow Termitomycesoriginated in Africa, and colonized Asia in some direct dispersals [overland] from Africa. How, then, did they get to Madagascar? It turns out that only those species that bring their own fungi to start a new nest are found in Madagascar. All the termites found there originated in one founding event and radiated into several new species after arrival. This means a single individual made it there and all species of termite on the island come from that one individual. The situation for the fungi is different—there are three separate groups, all with

representatives on the African mainland. It is still a mystery how that happened.

ز An excavated termite garden

showing all surfaces covered with fungal hyphae.

FUNGUS-ANIMAL MUTUALISMS

suggests that the ants started farming 55-60 million	so they either have to employ various protozoa and
years ago, so the agricultural mutualisms have evolved	other microorganisms in their guts, or—in the case of
over millions of years. This long process of coevolution	the Termitomycesgrowers—enlist the help of external
has led the ants and fungi to become irreversibly	mushrooms.
dependent on each other; the ants have lost their ability	As we can see from our own history, farming is a
to produce the amino acid arginine on their own, and	good strategy. The human population exploded with
the fungi have lost their ability to digest wood or bark,	the advent of agriculture around 10,000 years ago, and
relying instead on the leafy plant matter delivered to	agricultural termites and leafcutter ants appear to have
them by the ants.	had similar success, building enormous nests that can
As an incredible example of convergent evolution,	support millions of workers. From DNA sequencing
it has been found that Old World termites cultivate	and the fossil record we know that ant-fungus and
fungal gardens in a similar manner to the New World	termite-fungus mutualisms evolved independently,
ants. The termites cultivate the basidiomycete fungi,	maybe several times. We also know that while termites
Termitomyces, which benefits them in two ways: it serves	resemble ants morphologically, they arose far earlier, as
them directly as food, and it breaks down wood (in	did their mutualistic relationship with fungi—the
particular cellulose), which the termites can also feed	termite-fungus symbiosis is 30-50 million years older
upon. In its native form termites cannot digest wood,	than the ant-fungus relationship.

LESSER-KNOWN FUNGAL FARMERS	Possibly the weirdest fungus-farming bugs are
Bark beetles, termites, and ants are not the only insects	associated with the Black Bolete (Phlebopus portentosus),
to have coevolved with fungi. There are countless	which is a popular, albeit strange edible bolete from
species of wood-boring insects on the planet, none of	Asia. Boletes are thought of as being mycorrhizal,
which make enzymes to digest wood cellulose. Instead,	growing as symbiotic partners with trees or other living
they must live in a symbiotic relationship with microbes	plants, but the lifestyle of Phlebopus portentosusis far
that produce cellulase enzymes for them. One such	more complicated than that. If you were to locate a
example is the Giant Horntail wasp (Tremex columba),	Black Bolete in nature and carefully examine the base
which is a very large (roughly 2 inches [5 cm] long)	of its stalk you would find hyphae leading down into
wood-boring wasp of the family Siricidae. Like all	the soil, just as you would with any mushroom.
siricids, the Giant Horntail wasp relies on basidiomycete	However, rather than leading to a living plant root
white rot fungi as its enzyme-producing partner, even	tip (as with mycorrhizal fungi) or to decaying matter
transporting these fungi to the wood source. These	(as with saprobic fungi) the hyphae lead to a third
symbioses are mutualistic, as both partners benefit; the	organism: a gall-forming insect.
wasps get to utilize a large energy resource in the forest,	Insect galls are quite common on many kinds of
in the form of cellulose, while the fungus benefits from	plants, where they usually appear as outgrowths of plant
not only being transported to a specific host tree, but	tissue (much like a tumor). The gall typically serves as
past the tree’s first line of defense (the corky bark) and	a microhabitat for the larva of a gall-forming insect,
into the interior wood.	which is found inside, happily protected from predators

while it derives nutrition from its plant host. But this is

س Close up of a free-living mealy

bug (above). These are common

not the case with galls associated with the Black Bolete.

plant pests.

Although they grow on the host plant’s roots, the galls

ر The strange Black Bolete,

are formed from the hyphae of the fungus, rather than

Phlebopus portentosus, a popular

cultivated mushroom in Asia.

plant tissue, making them “fungus-insect galls.”

To date, six mealy bug species in the family Pseudococcidae have been identified that partner with Phlebopus portentosus, and together they utilize more than 21 plant species. The relationship between the fungus and the insect is tightly connected: the root mealy bug is unable to survive without its fungal protector, while the fungus gains extra nutrients from the bug in the form of honey dew. Having these two biotrophs parasitizing the roots doesn’t seem to matter much to their plant hosts—the infections seem symptomless.

MUTUALISTIC SYMBIONTS

Fungus-plant mutualisms

The vast majority of plant species form a mutually beneficial living relationship with fungi. Mycorrhizal fungi—not roots—are the chief organs of nutrient uptake by land plants.

FUNGUS-PLANT MUTUALISMS

× Mycorrhizal fungal hyphae grow	Mycorrhizal fungi are essentially benevolent parasites
outward into the soil and dramatically
	that benefit from plant lipids and carbohydrates, then
increase the absorptive surface of
plant roots.	reward the plant for its hospitality by supplying water,
	as well as essential nutrients such as nitrogen, phosphate,
	and potassium. Interestingly, mycorrhizal fungi are
	being found that have cellulase enzymes, which suggests
It is likely that symbiotic fungi have colonized the roots	they probably glean nutrition saprobically from decaying
of 90 percent or more of the world’s plant species, and	organic matter in the environment, as well as
pretty much all trees. Mycorrhizal (literally, “fungus-	biotrophically from their plant host.
root”) associations involve fungal hyphae that grow	The fossil record tells us that mycorrhizal
from within and around the roots of the host plant, and	associations date back around 460 million years, which
outward into the surrounding soil, increasing the surface	means they have existed for about as long as terrestrial
area of the root system several hundreds to thousands	plants. They likely played a key role in the invasion of
of times. Mycorrhizae are so common and fundamental	terrestrial habitats by aquatic plants, which would have
to plant nutrition that most plant species could not	been unable to survive the harsh conditions on dry
survive without their fungal partners unless there was	land until joining in symbioses with fungi. From these
some sort of artificial input to replace it (in situations	lowly beginnings, terrestrial plants proliferated, as did
where abundant water and fertilizers are added, the	mycorrhizal fungi. Indeed mycorrhizal associations have
plant may cast off its fungal partners, which is possibly	arisen several times, and while all mycorrhizas involve
why mushroom diversity is so much lower among trees	plant roots, the physiology can be quite different across
in urban settings).	the spectrum.

Mycorrhizal network

KEY

Much of the chemistry and physiology

Interspecific communication

that goes on in a forest occurs below ground, and hidden from our view. Plants rely on symbiotic mycorrhizal

Water and nutrients	Autotrophic
fungi for water and nutrient uptake	plant

from soils. Those same fungi get

Photosynthesis products

theircarbohydrates and other building

(carbohydrates, lipids etc.)

blocks of life from their photosynthetic partners. All the residents of the soil,

Microbiota found in the soil

plant as well as microbial, are

(bacteria, fungi and viruses)

“connected” by way of chemical cues.

Mixotrophic

plant

Saprotrophic

litter fungi

Symbiotic

Saprotrophic mycorrhizal

Soil	wood fungi

fungi

Moss

MUTUALISTIC SYMBIONTS

ECTOMYCORRHIZAL AND ENDOMYCORRHIZAL FUNGI	mantle over the surface of the root, nor do they
Ectomycorrhizal fungi grow into the plant root tissue,	produce large showy fruitbodies. In fact, most
but do not enter the root cells. Instead, hyphae grow	endomycorrhizal species produce no real fruitbody
around the outer cortical cells of the root forming what	at all—a few produce balls or clumps of spores in
is known as a “Hartig net.” Ectomycorrhizas (EcM, or	the soil, but many seemingly do not undergo sexual
“ectos”) exist most often as a mantle or covering of	reproduction, and may not even have the genes for it.
interwoven fungal hyphae on the surface of the fine	Given their cryptic nature, and the inability (for most
roots of trees; the mantle makes the root tips appear	species) to be cultured in the lab, most endomycorrhizal
swollen and can be visible to the unaided eye. EcM	fungi are poorly known. Ironically, what isknown is
fungi are associated with most conifers and many	that they dominate the planet and are probably the
hardwoods, including oaks, beeches, Nothofagus, and	puppet masters for all life on terrestrial Earth.
Eucalyptus. Well over 4,000 species of EcM fungi occur	By far the largest group of endomycorrhizal fungi
in forests across the globe, including many of our most	is the arbuscular mycorrhizal, or “AM,” fungi in the
prized edible fungi, such as boletes, chanterelles,	phylum Glomeromycota. Arbuscular mycorrhizas take
Amanitas, and truffles.	their name from the arbuscules (the highly branched
By contrast, endomycorrhizal fungi not only grow	structures that they form inside each root cell) where
into the plant root tissue, but penetrate the plant root	the exchange of water and nutrients occurs.
cells as well. Unlike EcM, they do not produce a thick	Endomycorrhizal associations involve a much broader

Mycorrhizal symbiosis

A close examination of tree roots will reveal ectomycorrhizal fungi growing as a sheath around rootlets, and penetrating

the roots to grow between the cells as well.

Epidermis

Cortex

Endodermis

Fungal hyphae between cortical cells (Hartig net)

Mantle

(fungal sheath)

س Orchid “roots” are more like stems and mostly function to hold the plant in place. Endotrophic mycorrhizal fungi grow from within the plant cells and into the substrate, taking up moisture and nutrition. A cross section of an orchid root shows mycorrhizal fungi (stained pink) visible within the plant’s cells.

ز Looking like little upside-down trees, arbuscules are seen inside of

root cells of Horse Gram plant

μm

(Macrotyloma uniflorum), a common legume grown in Asia.

MUTUALISTIC SYMBIONTS

array of plants than EcM, with some associations that	ENDOPHYTIC AND EPIPHYTIC FUNGI
are unique to specific groups of plants, such as alders,	Endophytic fungi (those that live within plants) and
orchids, and ericaceous plants (rhododendrons, azaleas,	epiphytic fungi (those that live on the surface of plants)
blueberries, cranberries, etc.). It is no coincidence that	have become a hot topic for research mycologists in
many of these plant species grow in boggy or nutrient-	recent years. Much remains unknown about these groups
poor soils, as AM fungi can scavenge nutrients from the	of fungi, but just about every plant group that has been
poorest of soils, including those that are rocky and arid.	investigated seems to have endophytic species living
As well as providing their host with drought	within it. These fungi appear to play key symbiotic roles
tolerance and an ability to survive in nutrient-poor	in the lives of their plant hosts, providing drought
soils, AM fungi are also crucial for building and	tolerance through plant-like hormones or producing
maintaining soils. It is therefore hardly surprising that	toxic compounds that protect them from mammalian
most plants—including grasses, cereals, vegetables, vines,	and arthropod herbivory. Endophytic and epiphytic
and bushes—are known to partner with AM fungi,	fungi also provide protection from plant diseases,
while quite a few form mycorrhizal associations with	including those caused by other fungi.
both AM and EcM fungi.	For scientists, biotechnology companies, farmers,

plant breeders, and foresters, studying the relationships

FUNGUS-PLANT MUTUALISMS

between endophytic/epiphytic fungi and their hosts	MYCELIAL NETWORKS
may lead to new methods of battling crop disease, the	An individual plant isn’t limited to just one mycorrhizal
discovery of novel chemical compounds, and clues to	fungus—it may have many different species connected
the impact of these fungi on biodiversity. As one	to its roots at any one time. Likewise, an individual
example, the cancer “wonder drug” paclitaxel (PTX)	fungus may be connected to multiple plants, including
was discovered in rare Pacific Yew trees (Taxusspp.).	those of different species. The result is a common
This discovery seemed likely to doom the slow-	underground mycelial network that has come to be
growing tree species, as harvesting the life-changing	known as the “wood-wide web.” As that might suggest,

compound from the tree’s bark led directly to the death of the tree. However, it was discovered that the source of the compound was not actually the Pacific Yew itself, but an endophytic fungus living within it. Further

ش The forest we see is only part of

discoveries revealed that several fungi of different	the picture. Belowground, there is an
	interconnected web of plant roots and
genera produce the same compound and that those	fungal mycelia—a wood-wide
	web—that transports water, nutrients,
fungi can be grown in culture, so the trees didn’t need
	and chemical cues about the
to be sacrificed.	surrounding environment.

this network not only transports water and nutrients,	Plants such as Ghost Pipes (Monotropaspp.) don’t
but also functions as a sort of “mycelial internet”—a	have chlorophyll and cannot photosynthesize, so it was
communication system where chemical information is	long assumed that they were either saprophytes that
shared between plants, and signals can stimulate a	obtained their nutrition from decaying organic matter,
common defense against soil pathogens, inhibit the	or were parasites of nearby green plants. In the 1960s,
growth of neighboring plants, and warn of insect attacks.	radioisotope experiments demonstrated the movement
Nutrition is also shared among plants by way of this	of carbon from spruce trees to Monotropa, but also revealed
common mycelial network, enabling understory plants	that fungi were involved in this carbon flow, making
and light-deprived seedlings on the forest floor to tap	the Ghost Pipe a secondary (epiparasitic) parasite.
in and benefit; Pacific Northwest Douglas-fir stumps	Epiparasitism is a clever adaptation, as it means that
felled by loggers can continue to live for decades	the parasitic plant is ultimately drawing carbon from
because their roots are connected to this network.	the rest of the plant community. It is assumed that
	mycoheterotrophs like Monotropamust be giving
TURNING THE TABLES	something back to their fungal partners in return
Mycorrhizal fungi undoubtedly evolved from parasitic	(although we don’t know for sure), but it seems
ancestors, but over time they have become far more	unlikely they are giving anything to the photosynthetic
benevolent. That a symbiont can shift from a parasitic to	plant symbionts. So why don’t these “cheaters” get
a mutualistic relationship with its host over evolutionary	caught? The problem is, plants are adapted to allow
time is expected; sometimes a symbiont may even be	infection by a large number of mycorrhizal fungi, and
mutualistic or parasitic at different phases of its life	they seem perfectly willing to allow the net flow of
cycle, or the life cycle of its host. In most of these	carbon to other plants via the wood-wide web. At the
relationships the host is a photosynthesizing organism	same time, it seems they are ill-equipped to detect any
(photobiont), but this isn’t always the way—some	cheaters in this system that are drawing carbon and
mycorrhizal plants turn the tables and are parasites	giving little—if anything—in return. Therefore, as long
of their fungal symbionts.	as the epiparasitic plant does not compromise the

fitness of the fungus, the long-term stability of its food source is assured.

Orchids function in much the same way, getting their sustenance from mychorrhizal fungi. Unlike other flowering plants, orchids do not make true seeds with a nutrient source (endosperm). Instead, orchid seeds are tiny, naked embryos about the size of a speck of dust. In order to begin germination these “seeds” need to be parasitized by their specific mycorrhizal fungus. This fungus is the only “root” the young plant has and is therefore the source of all its nutrition. However, in this particular relationship there is evidence to show that the orchids may be contributing to their fungal partner; it seems that orchid mycorrhizal fungi obtain proteins from orchid cells as they die and slough materials.

ر Indian Pipe (Monotropa uniflora)

plants are achlorophyllous and cannot photosynthesize. Shown here are flowers and greatly reduced leaves, no longer useful for catching light.

MUTUALISTIC SYMBIONTS

Lichens

Lichens more closely resemble small plants than fungi, and were in fact mistaken for plants until the second half of the nineteenth century. However, they are the third principle mutualistic lifestyle of fungi, with a remarkable story to tell.

LICHENS

In the latter half of the nineteenth century, Heinrich	Thanks to its symbiotic nature, many lichens can
Anton de Bary, Simon Schwendener, and Albert	thrive in extreme environmental conditions where no
Bernhard Frank all proposed that lichens were symbiotic	other photobionts can survive; specific lichen
in nature, and we now know they are comprised of a	communities dominate ecosystems such as the tundra,
mycobiont (fungus) and a photobiont (either an alga or	Antarctica, and coastal fog deserts. Consequently, most
a cyanobacterium, or both). That fungi are involved in	people would be unaware that lichens are the dominant
lichens becomes obvious when you consider that their	life form over a large portion of the terrestrial planet,
tiny sexual reproductive structures look very much like	with a few even growing submersed in freshwater or
those of their non-lichenized cousins; most look like	saltwater. However, like many other groups, their
cup-fungi, but some resemble mushrooms.	highest species richness is found in tropical rainforests.
The intriguing part of lichens is their vegetative	We don’t know exactly how many lichens coexist in
body, or thallus, which is very different to that of	tropical rainforests, but 600 or more individual species
non-lichenized fungi. Instead of a mycelium of hyphae	within one hectare is not unusual. No ecosystem on
overgrowing or penetrating the substrate, the lichen	Earth harbors more lichen species in a comparable area
thallus is often complex and compartmentalized. Much	and they colonize just about any surface: there are
of its structure is fungal and it functions to acquire	communities on leaves, on the fur of mammals, and
nutrients and house the photobiont, which plays a crucial	some longer-lived mantids support tiny lichen colonies
role by producing carbohydrates via photosynthesis.	that help perfect their leaf mimicry.

It takes a village

Cephalodium

A lichen is a community of photosynthetic organisms (usually algal cells) protected within a structure made of fungal cells. The photobionts photosynthesize when

Cortex

conditions are favorable and support all the symbionts with carbohydrates. The fungal tissues resist desiccation and hold fast to

surfaces by structures called rhizines.

Algal zone

Medulla

Lower cortex

ر Reproductive structures of lichens

resemble those of the mycobiont

Rhizines

involved, in this case an ascomycete cup fungus.

LICHENS

Lichens first appeared on Earth some 250-300 million years ago in the Permian. Dinosaurs came slightly later, during the Triassic, some 230 million years ago, but while the dinosaurs came and went, lichens are still around. What we can reconstruct about ancient lichens suggests that they have not changed much in general appearance. Notably, early diverging lineages of lichen-forming fungi are still found growing mostly on bare rocks, often in dry conditions that probably resemble those that lichens faced when they first appeared. Some of these lichens, such as the enigmatic rock tripes of the genera Umbilicariaand Lasallia, really give the impression of ancient life forms or “living fossils.”

There are currently around 18,000 lichen species, but many groups are poorly known and estimates of more than twice this number of species are not unrealistic. The vast majority of lichen fungi are ascribed to the Ascomycota, and almost one third of the currently known Ascomycota form lichens. Historically, the Basidiomycota (the other large phylum) was believed to contain very few lichen-formers, but this

picture has been changing in recent years. We now	algal genera Trebouxiaand Trentepohlia, but other
know that some lichenized basidiomycete groups are	cyanobacteria and green algae—and even some brown
as diverse as lichen-forming ascomycetes. One group in	algae—are also found in lichens.
particular—the genus Cora(family Hygrophoraceae)—	Ongoing research is continuously discovering new
contained just a single species until recently, but is now	photobiont lineages, as well as an increasing number of
thought to comprise more than 400 species.	lichen fungi that can partner with both green algae and
With modern molecular biology tools, our	cyanobacteria at the same time. In such situations the
understanding of the nature and composition of lichens	primary photobiont is the green alga, and the secondary
has accelerated, and the enormous genetic diversity	photobiont is the cyanobacterium, which is found in
found in lichen photobionts is starting to be	portions of the thallus called cephalodia (taken from the
appreciated. The most common lichen photobionts	Greek, kephalos, or “head,” as they may look like small
include the cyanobacterial genus Nostocand the green	heads). The benefit of this arrangement is that green

algae and cyanobacteria photosynthesize under different conditions and provide different types of carbohydrates. Importantly, cyanobacteria are able to fix atmospheric nitrogen, which is a crucial element in amino acids and

ض Looking every bit like offal,

other organic molecules, and allows lichens to grow in

the Rock Tripe lichen, Umbilicaria

nutrient-poor environments.

torrefacta.

It’s fair to say that lichens do some pretty amazing

chemistry. Although they behave like plants in many

ر German naturalist Ernst Haeckel

illustrated all manner of life forms in the

respects, their relationship with fungi is revealed by

mid 1800s, including lichens.

their diverse colors, which are caused mostly by pigments deposited in the upper portions of the lichen thallus. As early as 1866, the Finnish lichenologist William Nylander was using chemical characteristics to distinguish morphologically similar species, and this remains a valuable tool for their identification.

Of course, chemistry is found in all living organisms. However, while organisms share certain chemical aspects of their primary metabolism, such as respiration and photosynthesis, or the formation of carbohydrates, protein, and fats, each organism also has a specific secondary metabolism that is often unique to a particular lineage or found scattered in different groups. In lichens, the chemical substances produced by this secondary metabolism—the secondary compounds—play important roles in the biology of these symbiotic systems. For example, the pigments that produce the variety of colors of lichens serve as sunscreens, protecting the organism from damage through high UV radiation and enabling the lichen to grow under conditions where the photobiont or mycobiont could not exist on its own. Other substances, usually found in the inner portion of the lichen or medulla, have functions in the internal water and gas exchange of the thallus and may also function as anti-feedants.

Lichens have many different roles to play in the ecosystem, ranging from pioneers in soil formation, to regulating the water cycle and atmospheric humidity, to serving as biological fertilizers by fixing atmospheric nitrogen. Some animals have lichens on their menu as a principal food source, while a diversity of microorganisms and small animals call lichens “homes,” transforming them into miniature ecosystems themselves.

Humans find many uses for lichens, including in pharmaceutical drugs, traditional medicine, the production of dyes, and food. Lichens have also been shown to be very effective biological indicators of environmental health, with a decline of lichen diversity in urban areas correlating directly with an increase in lung cancer mortality rates. This is not because lichens prevent lung cancer, but because they respond in a similar way to pollution as humans do.

 In some habitats, it is common to see surfaces covered with many different lichens. Shown here on a twig are Lobaria pulmonaria(green-brown) and a Parmeliaspecies (gray).

MUTUALISTIC SYMBIONTS

CERRENA UNICOLOR

Mossy Maze

	SCIENTIFIC NAME	Cerrena unicolor
	PHYLUM	Basidiomycota
	ORDER	Polyporales
Polypore
	FAMILY	Polyporaceae
	HABITAT	Forest
Bizarre love triangle

At first glance, you might confuse the overlapping	incredibly long ovipositor to drill through the wood and into
clusters (“flabellae”) of Cerrena unicolorwith the	the tunnel of the horntail larva. An egg is then either injected
common Turkey Tail mushroom (Trametes versicolor),	directly into its larval host or deposited in the prey’s tunnel
both of which are found on rotting wood. However,	(this part is still not scientifically certain). Once hatched, the
a clear difference is the presence of algae growing on	ichneumonid larva feeds on the horntail larva, consuming it
top of this furry mushroom, which gives it a greenish	completely within a couple of weeks. Pupation then takes
color and the name Mossy Maze Polypore.	place within the host’s tunnel and the adult Megarhyssa atrata

emerges the following spring.

The lifecycle of Cerrena unicoloris also far more complicated and fascinating than that of Trametes versicolor, as it is part of a

 Cerrena unicolorvery often

symbiosis with two insect species: the Giant Horntail (Tremex

looks old and decayed due to its

columba), which is a mutualist of the fungus, and the Black	green color.
Ichneumonid wasp (Megarhyssa atrata), which is a parasitoid
of the horntail.
Megarhyssa atratais a member of the Ichneumonidae,
which is the largest family of insects (there are 3,000 species	Deadly huntress
in North America alone!). Ichneumonids are parasitoids	Female Megarhyssa wasps are

able to locate quarry deep inside

that live inside and ultimately kill their host. As most of their

rotting logs.

insect prey is minute, most ichneumonids need to be even smaller, but the genus Megarhyssais an exception: these are the Giant Ichneumonid Wasps. Megarhyssa atratais the largest species, with females growing up to almost 7.5 inches (19 cm) in length, taking into account their antennae

and ovipositor.

Ovipositor

The female Megarhyssa atratalocates the horntail’s woody lair by detecting chemical cues given off by its fungal partner,

Horntail larva

Cerrena unicolor. She alights on the rotting wood and vigorous “antennae sensing” ensues; it’s possible she can detect larval movement inside the wood. The wasp then deploys her

MUTUALISTIC SYMBIONTS

LABOULBENIALES

Beetle Hangers

	SCIENTIFIC NAME	Hesperomyces virescens
Animal symbionts	PHYLUM	Ascomycota
	ORDER	Laboulbeniales
	FAMILY	Laboulbeniaceae
	HABITAT	Forest and urban

One of the most bizarre groups of fungi that you have	mycologist Mordecai Cubitt Cooke, these fungi had been
probably never heard of is the order Laboulbeniales.	among innumerable insect collections and completely
Everything about these tiny ascomycete fungi is	overlooked for centuries—if noticed at all, they were
unusual, yet they comprise the largest group of fungal	presumed to be outgrowths of the insect, be it hairs or even
arthropod parasites, with more than 2,200 described	appendages. Heinrich Anton de Bary was likely the first to
species from 142 genera. They typically form species-	report them as fungal in nature, but it was the Harvard
specific symbioses; most labouls parasitize predacious	professor Roland Thaxter who made them his life’s work,
beetles (families Carabidae and Staphylinidae),	describing 103 genera and 1,260 species.
but other insects are known hosts, as are a few	To this day, new species are still being found, often
other groups such as mites and millipedes.	hidden in plain sight on collections made decades or
	centuries ago. In 2020, for example, Ana Sofia Reboleira,
In all instances the association is largely ectoparasitic and the	a biologist and associate professor at the University of
fungus penetrates its host’s exoskeleton with a very thin and	Copenhagen’s Natural History Museum of Denmark, was
hardly noticeable haustorium, so little or no damage is done.	looking at photos of North American millipedes that had
Although incredibly common and widespread, this	been shared on Twitter. Something about the bugs didn’t
inconspicuous group of fungi was only discovered in the	look quite right, so Reboleira and her colleagues compared
mid-nineteenth century. Dubbed “beetle hangers” by the	the photographs with specimens held by their own museum.

Sure enough, they discovered a new species of laboulbenialean fungus—the first ever to be found on an American millipede—

Take a closer look

which they dubbed Troglomyces twitteriafter the social

Upon close examination, what appears to be tiny

hairs or appendages on the insect’s exoskeleton

media platform.

are the thalli of laboul fungi. Each thallus produces spores that are fired onto an insect host, often during copulation.

Harmonia axyridis, known as the Harlequin or Asian Ladybeetle,

Fungal thalli

unwittingly hosts a large colony of

laboul fungi. Native to Asia, this beetle is now common all over the world, introduced as a control for aphids and many other insect pests.

Beetle elytra

MUTUALISTIC SYMBIONTS

TERMITOMYCES TITANICUS

Titan Mushroom

	SCIENTIFIC NAME	Termitomyces titanicus
Animal symbiont	PHYLUM	Basidiomycota
	ORDER	Agaricales
	FAMILY	Lyophyllaceae
	HABITAT	Forest

The largest known mushroom is the aptly named Titan	Although all termites eat plant matter, most rely on
Mushroom (Termitomyces titanicus). The stalk of this	microbes living within their gut to digest the cellulose for
gilled behemoth can reach several feet in length and	them. However, members of one termite group—the
caps can measure more than 3 feet (roughly 1 m) in	Macrotermitinae—no longer harbor gut microbes, and instead
diameter, making it a truly titanic fungus. However,	rely entirely on Termitomycesfungi to convert plant cellulose
the lifecycle of this prized edible is far more noteworthy	into digestible nutrition. The termites eat fresh plant material,
than any accolades for its size. Known from Africa and	which passes through their intestine and is molded to form
Southeast Asia, Termitomycesspecies are obligate	a substrate for the fungi, deep inside the labyrinthine nest.
biotrophs of termites, which farm them within their	Some termite species rely exclusively on the growing fungi’s
subterranean nests.	mycelia (and asexual spores) as food, while others ingest it to
	benefit from the enzymes that enable them to digest other
Their lifestyle is amazingly similar to that of the	cellulosic matter.
leucocoprinoid fungi cultivated by the leafcutter ants and	Not all species of Termitomycesare known to produce
relatives in the New World, demonstrating convergent	fruitbodies, but those that do start by growing a very long
evolution in a spectacular fashion (see pages 173-175).	“root-like” mushroom stem toward the surface. The
	mushroom cap is initially firm and pointed, with a hardened
	umbo (the bump on top of the cap), which enables the
Massive Mushroom	fruitbody to penetrate the wall of the nest and compacted
Fruitbodies of this species can	soil. It can then emerge above ground, where it can grow

grow to astounding size.

into a true giant.

feet (1 m) across

 A welcome find, Termitomyces titanicusare popular edible mushrooms in many places, including Zambia where this photo was taken.

MUTUALISTIC SYMBIONTS

BRYORIA TORTUOSA ANDBRYORIA FREMONTII

Horsehair Lichens

	SCIENTIFIC NAME	Bryoria tortuosa and Bryoria fremontii
Hiding in plain sight	PHYLUM	Ascomycota
	ORDER	Lecanorales
	FAMILY	Parmeliaceae
	HABITAT	Forest

Lichens are everywhere, but most people pay them	This was something that Toby Spribille set out to answer
little attention. However, what looks to be a mere	in 2011. Initially, Spribille couldn’t find any differences
discoloration on a rock or tree bark, or a fuzzy	between the two species when he compared them to known
outgrowth from some twigs is actually a fascinating	ascomycete gene sequences (the accepted fungal partner in
life form that’s casually going about its business. Most	lichens), so he broadened his search to include the genetic
of what you see is fungal tissue that has partnered up	sequences of all known fungal genes. This gave him a
with a photosynthesizing organism, and while it is the	match—not to an ascomycete, but to a basidiomycete yeast.
photobiont that carries out carbohydrate synthesis,	Although completely unknown to science, a basidiomycete
it is the mycobiont that is pretty much calling the shots.	yeast was hiding within the lichen and seemed to be the key
	in bringing together the ascomycete and the photobiont.
That’s been the story for more than a century, but it turns out	Hidden in plain sight for centuries, the inconspicuous fungus
that everything we thought we knew about lichens may have	could only be seen within the lichen tissues with the aid of
been wrong. Researchers have long puzzled over the fact that	a fluorescent dye that is specific to basidiomycete cells.
you can bring together the relevant fungal and photobiont	Research is ongoing, but many other lichen species have now
partners in a lab, but rarely get them to form a lichen.	been found to harbor very specific yeasts as a third partner.

Furthermore, differences between lichen species cannot always be explained by genetics. Take, for example, the ascomycete lichens Bryoria tortuosaand Bryoria fremontii. The former produces the mycotoxin vulpinic acid, and is deadly, while the latter has long been used as food. Yet despite their very different behaviors and appearances, studies showed they both consisted of the same fungus paired with the same alga. So what was it that made them different species?

 Bryoriaspecies of lichens often

resemble hair growing from a tree.

MUTUALISTIC SYMBIONTS

PORODAEDALEA PINI

Conifer Maze Conk

	SCIENTIFIC NAME	Porodaedalea pini
Habitat creator	PHYLUM	Basidiomycota
	ORDER	Hymenochaetales
	FAMILY	Hymenochaetaceae
	HABITAT	Forest

As the cause of Red Ring Rot, Porodaedalea piniis	The Red-cockaded Woodpecker is a keystone species in
the most important fungal pathogen of conifer trees	sensitive southern Longleaf Pine ecosystems, which are areas
in the Northern Hemisphere—even if an infected	prone to fires. To protect itself from fire and pathogens, the
trees doesn’t die it is rendered useless for commercial	tree has a variety of adaptations, including the production of
harvesting, while the internal decay makes trees	copious amounts of resin (much more than most other pines).
hazardous in recreational or public areas. At the	This resin is also manipulated by Red-cockaded
same time, though, the fungus is beneficial to many	Woodpeckers, who maintain resin wells to keep predators
organisms in the ecosystem.	like snakes away from their nest cavities.

Fungi—especially those that can rot wood—are habitat modifiers for a number of disparate groups of animals, and trees that are rotting from the inside-out serve as an important habitat for innumerable arthropods, as well as cavity-nesting birds and mammals.

To avian species that excavate cavities into the stems and branches of trees, wood decay fungi are a crucial symbiont. In North America, the associations between fungi and endangered Red-cockaded Woodpeckers are particularly interesting because these are the only birds that specialize in excavating the heartwood of living pines. This process can take years to complete, but in trees that have been attacked by Porodaedalea, nest cavity construction takes a fraction of the time. Because of this, the birds recruit the fungus directly, carrying it from tree to tree, inoculating as they go. The location of their subsequent nest cavity construction is not random, either. The shelf mushrooms are a sign to the birds that this is where the fungal colonization has been most active and where the wood will be softest, so the birds start excavating directly

 Fruitbodies of Porodaedalea

beneath fruitbodies on the sides of host trees.

pinipolypore.

MUTUALISTIC SYMBIONTS

GYRODON MERULIOIDES

Ash Bolete

	SCIENTIFIC NAME	Gyrodon merulioides
Strange symbiosis	PHYLUM	Basidiomycota
	ORDER	Boletales
	FAMILY	Paxillaceae
	HABITAT	Forest and urban

The genus Fraxinus(ash trees), includes many species	that was first seen in the Detroit, Michigan area in 2002.
that are found throughout North America, Europe,	The adults—iridescent green beetles about the size of a grain
and Asia. White Ash (Fraxinus americana) is	of rice—feed on the tree’s leaves and lay eggs on the bark.
widespread across much of eastern North America	The hatched larvae burrow through the bark into the phloem
where it hosts a decidedly weird mushroom—the	tissues that transport water and nutrients, eventually killing
Ash Bolete (Boletinellus[=Gyrodon] merulioides).	the tree. To date, this diminutive borer has attacked and killed
The Ash Bolete is common on lawns and in parks,	tens of millions of trees in at least 35 states, mostly in the
always in close proximity to its host tree, but it is not	eastern and central USA, as well as infesting southern Canada.
normally of much interest to anyone. However, look	In 2017 the International Union for Conservation of Nature
beneath the ground where this fungus is attached to	(IUCN) declared that six North American ash species had
the tree’s roots and things get interesting.	become endangered or critically endangered because of

the tiny beetle.

Although it was long considered a bolete, the phylogeny of Boletinelluswas uncertain, so this group of mushrooms has shuffled among various taxonomic groups. About the only thing that was certain about this fungus was that it

was mycorrhizal, just like all boletes were thought to be— but it turns out that even this wasn’t true!

Upon close inspection, the mushroom is actually a symbiont of an aphid that lives as a parasite on the roots of the tree. The fungus seems to afford the tiny bug some protection by growing around the insect and forming dark black galls on the roots of the host trees. That’s right: the aphid is inside the hyphal galls, feeding on the tree, and the fungus seemingly gets all its nutrition from the insect.

Sadly, ash trees are in decline in parts of North America,

 Almost nothing about the Ash

as they fall victim to the Emerald Ash Borer (Agrilus

Bolete is conventional. From above

it looks like any other bolete but the

planipennis), and as the trees decline, so does the marvelous

underside features a bizarre merulioid,

Ash Bolete. The Emerald Ash Borer is an invasive beetle

or veiny hymenium.

FUNGI & HUMANS

A changing planet

Our natural areas are under threat: climate change, habitat loss, invasive species, and a loss of biodiversity are just a few of the challenges they face. These threats not only impact on the health of the planet, but on all life—including us. In this chapter we’ll take a look at these problems and examine how fungi might come to our rescue.

Interest in our natural world in general, and in wild mushrooms and foraging specifically, has seen a dramatic uptick in recent years. This is helping to call attention to the importance of our natural areas, which

ش More and more people are taking

to the great outdoors and foraging for

is no doubt a very good thing. But it’s also brought to

wild mushrooms, simply for the

purpose of education or photography,

light that our natural areas are under pressure from a

as well as for culinary use, is on the

variety of stressors, some old and some more recent.

dramatic increase worldwide.

The first thing that comes to mind when considering stresses to our local natural areas is that they’re being loved to death; as more people head off into the woods to forage, hike, or just to get away from the hustle and bustle back home, this impacts our wild areas.

On a wider scale, global climate change and its effects have been studied for decades. We know that the habitable geographic ranges of species are changing: some places are becoming inhospitably hotter or wetter/drier, while others that were once too wet/dry or too cold, are now becoming more favorable. This will also leave some species with no favorable habitat, and those species will inevitably go extinct.

A changing climate has led to other observations as well, and the rise of social media is playing a particularly useful part in allowing us to see things globally and in real-time. We are already seeing that the flowering times of many plants have been recorded earlier and earlier, and some plants are now blooming twice in a season. Although fungi are mostly hidden throughout the year and harder to study than plants, they seem to be following the same patterns— mushroom fruiting times are happening earlier in the year with some species, while others are fruiting twice per year.

FUNGI & HUMANS

THE CARBON CRISIS	Scientists are now coming to the conclusion that
The problem is carbon. Or, more precisely, carbon	an effective way to pull carbon dioxide out of the
dioxide. The global climate has been warming for a	environment, while at the same time increasing our
long time, but humans have drastically accelerated it	crop plant production, is to employ agricultural
through the burning of fossil fuels that pump tons of	practices that favor these beneficial soil fungi. AM fungi
carbon waste into the atmosphere. At 416 parts per	dramatically increase the effective root systems of plants
million, the concentration of carbon dioxide is higher	by producing a vast network of nutrient- and water-
now than it has been for millions of years, and is	absorbing hyphae. These hyphae greatly increase the
perhaps rising faster than ever before.	plant’s rhizosphere (the area of soil around it that it
There is, however, a movement afoot to fight global	influences), directly absorbing organic nutrients from
climate change head on, and one of the most powerful	the soil and increasing primary production (and
tools in its arsenal may just be a fungus. As discussed	therefore carbon accumulation) in both healthy and
earlier (see page **), arbuscular mycorrhizal (AM)	stressed environments.
fungi are poorly known. Just about the only thing we	These fungi are also important soil producers, and
know about them is that they are found all over the	along with their associated soil microorganisms they
planet and seem to partner with most plant life. This	produce a sticky protein called glomalin. Glomalin can
includes the formation of symbiotic relationships with	be thought of as an organic “glue” that creates a stable
the majority of our important crop species.	soil architecture that allows air, water, and roots to

ر Soil samples collected from different parts of North America; differences in soil composition confer different colors.

ض Glomalin, extracted from soil.

ز A microscopic view of a corn root shows the presence of arbuscular mycorrhizal fungi. The round structures are spores among filamentous hyphae. Coating everything is glomalin, revealed by a green antibody stain specific for this compound.

A CHANGING PLANET

move easily through it; without good structure, soils are prone to water loss (as well as saturation) and vulnerable to erosion.

Glomalin can also catalyze carbon sequestration and carbon storage in soil. As much as 30-40 percent of a glomalin molecule is carbon, which means this glycoprotein may account for as much as one third of the world’s soil carbon—more carbon than all of the plants and the atmosphere combined. Consequently, AM fungi could play a crucial part in combating global climate change, and this discovery is causing a reexamination of climate change modeling. As mycorrhizal fungal activity has such a large influence on the huge pool of carbon in our soils, climate change models are rapidly incorporating new data on mycorrhizal fungi, glomalin, and soil carbon storage into predictions of global warming rates.

FUNGI & HUMANS

ر Healthy soils with organic matter team with fungi.

ز Agricultural fields, seen from above.

However, while glomalin can last for decades in	mycorrhizal fungi, and nitrogen can also be added back
undisturbed soil, heavy tillage can reduce it dramatically,	to the soil by rotating crops with legume plants, such
along with its associated mycorrhizal fungi. Certain	as clover, alfalfa, peas, and beans. Reduced chemical use
pesticides, chemical fertilizers, compaction, organic	in the organic system also provides an environment
matter loss, and erosion can also reduce or eliminate	that is more favorable to the spread of mycorrhizal
mycorrhizal activity in the soil. Without the binding	fungi and associated microorganisms, and the
power of mycorrhizae, the soil structure deteriorates,	production of glomalin.
reducing the good microbial populations, and releasing
carbon dioxide into the atmosphere. By destroying	THE WORLD ON FIRE
large segments of the soil food web, the grower is also	There is overwhelming evidence showing that as the
then forced to use more fertilizer and cultivation in a	oceans warm, many coastal regions will experience
damaging feedback loop.	dramatic increases of moisture, inundation (as melting
Breaking out of this downward spiral will require	polar ice leads to rising sea levels), and a rise in the
more benign practices that favor mycorrhizal fungi,	frequency and strength of storms. At the same time,
and these practices apply to commercial growers as	inland areas will experience hotter and drier years, and
well as homeowners and backyard gardeners. We know	these will result in more frequent wildfires. These grim
that soils farmed with organic systems have greater	scientific predictions are already being borne out; for
populations of mycorrhizal fungi, and all growers can	North America, 2020 was the worst year ever for all
encourage their growth. Overwintering cover crops	of these calamities. The same year, Greenland and areas
can be used to supply energy that fuels the activities of	above the Arctic Circle experience unprecedented

wildfires, pretty much all of Australia was on fire, and Brazil lost more than 2.7 million acres—an area about the size of the U.S. state of Connecticut—to fire. Less than one year later, huge fires were consuming much of Patagonian South America.

Wildfires around the globe have caused tremendous losses to human life and property, and are inflicting lasting damage on species and ecosystems. In 2020 alone, the U.S. states of California, Oregon, and Washington saw fires consume around 7,700 square miles (20,000 km²), killing at least 35 people. In Australia the damage was even more epic: from September 2019 to March 2020 (the region’s summer fire season), more than 42,000 square miles (110,000 km²) burned, and a staggering 20 percent of the nation’s total forest cover was lost. Even normally

س Bushfire smoldering in

Australian Outback.

fireproof rainforests and wetlands were scorched.

Not only does this loss of habitat threaten species	fire to thrive. Fire can also exterminate invasive species
with small populations or restricted ranges (likely	that should have never been there in the first place.
leading to extinction for some), but it could potentially	However, the extensive and frequent fires that have
lead to permanent ecological changes if burned	been seen in our recent history have had an overall
landscapes fail to rebound. A report by the Australian	negative impact. Already there are some ecosystems
government estimates that 114 threatened plant and	in North America that have experienced frequent or
animal species lost 50-80 percent of their habitats	intense burns that are not regenerating, and in many
during the 2019-20 fire season, while 327 species saw	places the loss of vegetation has led to new invasive
more than 10 percent of their range burn. As a result,	species moving in. In some areas, such as the sagebrush
scientists are asking the Australian government to	ecosystem of the Great Basin, east of the Sierra Nevada
expand its endangered species list; at least 41 vertebrates	mountain range, and the forests in the Klamath Mountains
that were not endangered before the fires now face	along the California-Oregon border, invasive shrubs or
existential threats, and an additional 21 that were	grasses appear to have taken over completely.
previously listed as threatened might now need even	Just as fungi are a key component to healthy living
greater protection.	forests, so they can also play a key role in post-fire
Of course, some ecosystems have long been	restoration. Of about 430 species of ascomycetes in the
fire-prone and there are some organisms that require	Pacific Northwest, more than 100 species require a

FUNGI & HUMANS

FOREST MOSAIC

There is no easy way to solve the problem of ever bigger and more destructive wildfires, but one thing is clear: we must return the forests to a more natural life—and death. If there is one word that defines natural forests it is “mosaic.” A mosaic forest canopy and ground cover is something that you can see at ground level as well as from the air; it is a patchwork of old and young trees, burned and unburned areas, and varying amounts of carbon sequestered in the soils. Until now, many forests have been managed to maximize timber production, so openings in the forest, small burned areas, and over-mature trees have all been seen as “inefficient” to the commercial forester—far better to them is a vast, unbroken stand of even-aged trees. Yet when fire comes to these unnatural stands of forest

س Aerial view of a healthy forest

(and it will, eventually) the result is an unnaturally large and destructive fire.

with trees of varying ages and gaps.

forest fire to produce fruitbodies, many of which are	Geopyxisis seen as a harbinger of the next fire
quite small and are easily unnoticed. There are larger	mushrooms to emerge—the Burn Morels. Morels are
basidiomycete fungi that also seem to fruit only after	big business, highly sought after, and as such are well
a fire, including species of Pholiota, Psathyrella, Inocybe,	known among pyrophilous fungi. Pholiota highlandensis
Tricholoma, Clitocybe, and other genera.	is often the first gilled mushroom on the scene, right
Sometimes called phoenicoid fungi (for their ability	after the morels; unlike most species of Pholiotathis
to rise from the ashes like the phoenix of legend),	fire-loving species lives as an endophyte partner within
pyrophilous (“fire-loving”) fungi are found all over the	forest plants, but fruits only after devastating fire.

planet and on every continent except Antarctica. Most are poorly known, but as they come under increasing scrutiny, their crucial role in healthy forests is being discovered. One of the most-studied and most important is the little stalked cup Geopyxis carbonaria, which is a mycorrhizal symbiont of most forest conifers. You’re unlikely to see it most of the time, except after a wildfire, when it is usually the first

س Pholiota highlandensisis

mushroom to carpet a burned area in the spring.

a post-fire pioneer species.

EDGE OF EXTINCTION	with many of the species that both formed them and
The consensus of biologists is that we are rapidly	lived within them. How many species have been lost
destroying the life-support systems of Earth, making	is impossible to know, because we have identified no
our own future uncertain. Ecosystems are complex	more than 10 percent of the estimated tens of
sets of organisms that make up our living landscape,	thousands of species in those habitats. It is therefore
regulating the atmosphere, water, and soils, and serving	likely that most species that were lost will forever
as the source of our food, medicines, and many other	remain unknown.
essential products. But the planet’s ecosystems are	The main causes of these losses are habitat loss,
becoming less diverse, less complex, and falling apart	overdevelopment, and climate change, and unless we can
as, one by one, their constituent species are lost.	control these (and other underlying causes) we are in
In 2020, a United Nations Summit on Biodiversity	danger of losing 80 percent or more of the world’s species.
concluded that around 1 million of the estimated 8.5	This is a similar proportion that was lost 66 million years
million species of plants, animals, and other organisms	ago when the dinosaurs became extinct and many of
are in imminent danger of extinction, and that as many	the plants and animals that we know today began their
as half of the populations of organisms that existed 50	ascent. Because of this, most scientists agree that we
years ago are already gone. This loss of biodiversity	have entered the world’s sixth major extinction event.

seems to be accelerating. Over the past 25 years, about one quarter of all tropical forests have been lost, along

A CHANGING PLANET

ص Aerial view of Kaz Mountains gold mine and deforestation in Turkey.

س Amanita muscaria, commonly known as the Fly Agaric or Fly Amanita, here located in the Mount Lofty Botanic Gardens in the Adelaide Hills, South Australia. The protected gardens are a beautiful haven for these kinds of fungi and a home to kangaroos, echidnas, many species of birds, and a wide variety of flora.

ز Crowded living conditions in Hong Kong.

FUNGI & HUMANS

Although many countries have a “Red List” for	examined them using molecular techniques, found that
endangered species, which signifies that things are very	this mushroom was present pretty much everywhere.
wrong for a habitat, most of these do not include fungi	It just doesn’t often create fruitbodies. So the mycelium
(including in the USA, where I reside). The problem is,	is common throughout European forests, but it is only
fungi are enigmatic. Unlike an elephant or a whale, or	ever seen on those rare occasions when it pokes a spiny
some other fairly obvious large mammal, it’s much	fruitbody out of a tree. No one knows why it appears
harder to know whether a fungus is truly uncommon,	so infrequently, and until recently, no one even knew
or if it simply fruits infrequently and is rarely seen as a	it was there. Thus we still have a long way to go toward
result. Take, for example, Creolophus cirrhatus. This tooth	inventorying our fungal biodiversity and there is much
fungus lives as a tree saprobe, but it is rarely seen and is	that remains hidden—sometimes in plain sight.
therefore considered endangered; in Europe it’s a Red	What is clear, though, is that a loss of biodiversity
List species. However, recent studies of wood rot fungi,	is a serious stressor of the planet and it is something
which took wood samples from multiple sources and	that needs to be tackled now. The path forward is clear.

We must curtail overdevelopment and habitat loss, and continue with—or better, accelerate—the ongoing survey of the planet’s biodiversity. For species in decline we have to do our best to determine what’s going on

ز A quick survey of many forests

turns up a diverse array of mushrooms,

and turn that around. In many instances the solutions

lichens, and mosses.

may not be straightforward, just as the reasons for an

ش Rare, or simply rarely seen?

organism’s decline may be complex. But complex

Creolophus cirrhatusis a beautiful

but enigmatic fungus.

problems are not necessarily unsolvable.

A CHANGING PLANET

FUNGI & HUMANS

Fungi in our homes and gardens

Despite the production and deployment of the best technology and oceans of chemicals, it is estimated that pests—including fungi—consume more than 50 percent of the food produced on Earth. But are they really the enemy we think they are?

FUNGI IN OUR HOMES AND GARDENS

ر Fresh fruit often is consumed

before we get a chance to do so. You cannot see them, but the spores of fungi are in the air all around us. Wherever they settle could become a source of nutrition.

× An abandoned home quickly falls into disrepair; fungi jumpstart the decay.

That half of global food production is lost before it	leather, or just about any other natural material.
reaches our dinner plates is a truly startling figure, which	Without vigilance, fungi will attack and things
includes losses to crops in the field, as well as post-	will degrade—priceless museum collections, antiques,
harvest and in storage. Yet when it comes to combating	and libraries are all at risk of damage. Left at room
fungi, the answer appears to be quite simple: fungi need	temperature, fruit and dinner leftovers will spoil quickly,
moisture to thrive, so the preservation of food (as well as	and while refrigeration will slow the process down, it
our clothing, homes and contents) requires little more	will not stop fungi (or other microbes) completely;
than maintaining absolutely dry conditions.	even in your refrigerator your food is slowly rotting,
Putting this into practice is not quite so easy,	minute by putrescent minute. In fact, fungi will
though, because if anymoisture is present, fungi can	ultimately consume or destroy nearly everything within
turn almost anything into a food source. That includes	eyesight of where you are sitting right now and—given
items made of cellulose (cotton clothing, books,	the chance—a number of fungi will grow on and in
carpeting, even the paper backing on wallboard), wood,	the materials that your home is constructed of.

FUNGI & HUMANS

BENEFICIAL FUNGI	It is more than a little ironic that while the U.S.
Yet as destructive as fungi can be, scientists have figured	Army were trying to find ways to fend off the fungal
out ways to turn some of them to our advantage.	enemy, modern cotton cloth textile manufacturers
Trichoderma reesei, for example, is used in industry to	now employ Trichoderma reeseias an ally. The fungus is
produce cellulase (enzymes that degrade cellulose).	grown in huge tanks for the cellulases that it excretes,
All of the strains of this fungus that are used	with much of the enzyme going to denim jean
industrially come from a single isolate that was	manufacturers who use it to get the fashionable
collected in the Solomon Islands during the Second	“stonewashed” look (stones or pumice are sometimes
World War. At that time, the fungus was the cause of a	used to lightly abrade and soften the denim material,
serious problem for the U.S. Army: it was destroying	but cellulase enzymes give a similar result at a lower
the canvas tents used by the soldiers stationed in the	cost). Cellulase enzymes have many other uses, too:
damp jungles there.	they are widely used in detergents, textiles, pulp

, food, and livestock feed industries.

More recently, enzymes derived from fungi are being seen as a possible solution to our dependency on fossil fuels, by helping in the production of biofuels.

س Denim jean manufacturers use

Trichoderma reseito achieve a

Currently, most ethanol comes from fermenting the

stonewashed effect.

sugars produced by plant fruits (primarily grain), but

ز Transmission electron micrograph

plant biomass—which includes grass and wood—is

allows us to peer inside the cell of

Trichoderma reeseifungus.

potentially a much larger source. The problem is

breaking down all the plant cellulose and converting it

into fermentable sugars, which is where fungal cellulase

BIOFUEL BOON

enzymes (and Trichoderma reesei) can help.

Meanwhile, researchers in India have demonstrated that

The main fungi behind many of these applications the ascomycete fungus, Metarhyzium anisopliae, produces

are from Trichoderma, a huge, cosmopolitan genus that

copious amounts of lipase enzymes that break down fats

contains what are often the most rapidly growing and	and lipids. This has potential applications in the low-cost
dominant soil fungi. Many are pathogenic species of	production of biodiesel fuel, so who knows, perhaps fungi
plants and other fungi, and are common contaminants	will make biofuels a realistic fuel option in the coming years?

in mushroom farms—you have likely seen these green molds on fresh Shiitake mushrooms brought home from the market.

FUNGI & HUMANS

Paradoxically, some species are welcome in growing	genus Arthrobotrys, which are known for the elaborate
operations where they grow epiphytically on plant	nets and snares they use to trap nematodes. You can
surfaces and exclude other, more pesky fungi. In a	read more about these on page 234.
practice analogous to releasing ladybugs to control	Foresters also rely on beneficial antagonistic fungi
insects, growers can apply commercially prepared	to tackle Heterobasidion annosum. This is a widespread
mixtures of these good fungi as “biocontrols” for	and serious heart rot fungus, which left unchecked can
pathogens. Trichoderma harzianum, for example, is	spread from a cut stump to healthy trees through root
deployed in agricultural field settings to combat other	contact. However, spraying freshly cut tree stumps with
fungi, while Metarhyzium anisopliae(a close relative),	a simple spore suspension of the pretty saprobe Phlebia
is used in commercial preparations to control many	gigantea(also known as Peniophora gigantea) is all it takes
different kinds of insects in the home and garden,	to inhibit colonization of the pathogen.

including ants, termites, and thrips. Metarhyzium acridum is another “biopesticide” that is applied to fields to kill insects, especially plagues of grasshoppers in Australia, where the product is known as Green Muscle and Green Shield. However, perhaps the most interesting soil fungi used to control crop pests are species in the

ص Fungus Trichoderma harzianum growing in culture.

س Phlebia giganteagrowing in culture.

ز Metarhizium anisopliaeis being commercially-developed as a natural control of many insect pests, like this stinkbug.

FUNGI & HUMANS

Unwelcome fungi

A warming climate will doubtless be disastrous to many organisms, but for others it’s a boon. During long periods of environmental homeostasis these rogues may just hang on, but when there are periods of climatic upheaval they can flourish.

UNWELCOME FUNGI

Many invasive species seem to be benefiting from a	muscaria, also seems to be on the move, traveling around
warming environment. Recent research shows that	with certain timber species that are grown in tree farms
some invasive species are able to complete their life	and plantations. The concern is that this mushroom
cycle and reproduce at younger ages, while others see	will become naturalized and outcompete other native
an acceleration in population growth due to their	mycorrhizal fungi, with unknown effects on the native
increased overall fitness (measured by the average size	trees. Similarly, eastern North America is starting to see
of reproducing individuals, an increased proportion of	the Golden Oyster mushroom (Pleurotus citrinopileatus)
individuals that survive to reproduce, and an increased	naturalizing and spreading in some forests, again with
fraction that reproduce).	no idea of the impact this might have.
However, when it comes to invasive species, most	Once established, invasive species are very difficult
people probably don’t think about fungi. Larger and	to remove, which is why any action against them needs
more visible organisms typically make the headlines:	to be taken at the earliest opportunity. This was not the
murder hornets on the American West Coast, Asian	case a century ago, so it is unlikely that we will be able
carp in the Midwest, and Pablo Escobar’s hippos in	to turn back the clock on many or even most invasives.
South America. But it’s likely that the majority of our	However, educating and involving the public can at
problematic invasive species are fungi. We have already	least help to keep existing pests in check, and limit the
seen examples of emerging fungi that are wiping out	spread of new ones. People are becoming more and
susceptible amphibians and bats; having a devastating	more aware that our environment is under attack from
effect on crops, threatening world food security in the	invasives, and are already actively removing invaders
process; and killing off forests. This is caused both by	from their local parks and woodlands; there are even
the accidental spread of hardy fungal spores into new	clubs organized for this purpose.

due to the globalization of trade, and the disruption of natural environments that create the perfect breeding grounds for new fungi to evolve.

Even a few mushroom species are causing concern. Amanita phalloides—the notorious Death Cap—seems to be spreading around the globe, making headlines wherever it is mistaken for other edible species. Another Amanitamushroom, the European Amanita

ر The edible Golden Oyster

mushroom (Pleurotus citrinopileatus). Beautiful but spreading in areas of eastern North America.

FUNGI & HUMANS

SERPULA LACRYMANS

Dry Rot Fungus

	SCIENTIFIC NAME	Serpula lacrymans
Home wrecker	PHYLUM	Basidiomycota
	ORDER	Boletales
	FAMILY	Serpulaceae
	HABITAT	Forest and urban

When you think of all the calamities that cause damage	The result is an increase in the water content of otherwise
and destruction to human dwellings, common molds	completely dry wood, which facilitates colonization in areas
probably do not rank highly on the list. Hurricanes,	that were previously unfavorable. Wood decomposition
tornadoes, floods, and fires all make the headlines,	subsequently creates additional water as a by-product of
but pervasive damage to buildings by molds and	fungal catabolism and respiration, acting as a feedback loop
other fungi goes largely unreported. Yet it is a very	for further colonization.
real threat to timber constructions worldwide. The	Serpula lacyrmanscan show up anywhere that wood
most destructive of all the wood decay fungi is the	is present, and even an increasing amount of synthetic
cosmopolitan Dry Rot fungus, which wreaks destruction	materials used in modern construction doesn’t seem to deter
from the Americas to Europe to Australia.	it; this fungus can utilize several inorganic materials for its

nutritional needs, including calcium and iron ions extracted

bane of humanity has likely been living with us ever from plaster, brick, and stone. since humans began creating dwellings from wood—Dry Rot

even mentioned in the Bible. As humans spread around the globe, this fungus has traveled along with them, adapting nicely and seemingly benefiting from humanity.

Strangely, the cause of the destruction—Serpula lacyrmans—is all but unknown in nature. No one knows why it is rarely seen in the wild, but it may be that it doesn’t compete well with the myriad other microbes fighting for the same carbohydrates of dead wood. However, Dry Rot is keenly adapted to life in the dried timbers of our homes, although its common name is something of a misnomer; it may attack wood that has never been damaged by water, but the organism itself requires water, just like any other fungus.

To help it with this, Serpula lacyrmanshas the amazing ability

 Pretty but so destructive, the

to transport water (as well as nitrogen and other nutrients)

Dry Rot fungus almost seems to ooze

over woody surfaces where it weakens

by way of mycelial cords or rhizomorphs, often over great

and ultimately destroys the integrity

distances and even through the foundations of homes.

of the wood.

FUNGI & HUMANS

BOTRYTIS CINEREA

Noble Rot Fungus

	SCIENTIFIC NAME	Botrytis cinerea
Delicious chemistry	PHYLUM	Ascomycota
	ORDER	Helotiales
	FAMILY	Sclerotiniaceae
	HABITAT	Vineyards and urban

Botrytis cinereais a ubiquitous food spoilage mold that	wine. The first mold (Botrytis cinerea) infects the grapes in
is probably responsible for ruining more refrigerated	the field and turns them into raisins. The botryticized grapes
fruits and vegetables than any other microbe. Given	are then harvested and added to young dry wine, and the
enough time, this fungus can—and will—spoil any	mixture is left to ferment in barrels stored in underground
piece of fresh fruit in your home. When you go	cellars. During the aging process the surface of the wine
away for the weekend and come home to find the	blooms with a third fungus, Zasmidium cellare, which is a
strawberries you’d left in the fridge wearing fur coats,	common black mold resident on subterranean cellar walls
they didn’t don them to stave off the cold—that’s	(see pages 82). Each fungus contributes complex aromas
Botrytis cinerearotting them.	and flavors, unique to the style of wine.

This fungus is commonly found outside the home too, where it’s a serious pest to growers of many crops, including grapes. But it is not always destructive. Under the right conditions, certain grape varieties are magically transformed when they are infected by “Noble Rot,” and rather than being spoiled, they produce wines fit for nobility.

So how does the fungus work its magic? During infection, the fungus pierces the grape’s skin, which allows moisture to escape and causes the infected grapes to shrivel into raisins (similarly, frozen shriveled grapes are used to make ice wines). The water loss concentrates the sugars and flavors, and those flavors are transformed further by the Noble Rot fungus.

The most famous “botryticized”wines are the Sauternes of France’s Bordeaux region, which have been made this way for a couple of hundred years, and the Tokays of Hungary and

Slovakia, which have been produced for nearly four centuries.

 Up close and personal with the

However, while two molds are needed to make Sauternes

mold Botrytis cinerea. It’s hard to

believe that this homely creature is

wines (regular brewer’s yeast plus Botrytis cinerea), three fungi

responsible for heavenly Sauternes

are necessary for making the most famous styles of Tokay

wines.

FUNGI & HUMANS

ARTHROBOTRYS DACTYLOIDES

Lasso Fungi

	SCIENTIFIC NAME	Arthrobotrys dactyloides
Farmer’s friend	PHYLUM	Ascomycota
	ORDER	Orbiliales
	FAMILY	Orbiliaceae
	HABITAT	Farmland

Fungi have evolved all sorts of curious lifestyles, but	Arthrobotrysproduce coils and loops of hyphae that resemble a
possibly the most interesting—and gruesome—are	sticky net, coated with an adhesive, while other species create
the fungi that are predators of animals, particularly	loops that act as a “lasso”—when a nematode attempts to swim
nematodes. Nematoda is one of the largest groups of	through, the loop quickly constricts on the unsuspecting prey
invertebrate animals, with many thousands of named	holding it tightly. The constricting hyphal rings created by
species. These very small round worms go mostly	Arthrobotrys dactyloidesare formed from three cells and all it
unnoticed because of their minute size, but they can	takes is the sensation of a nematode passing through to set
be found in just about any situation, and range from	them off (heat has also been demonstrated as a trigger under
saprobes to pathogens that attack our agricultural crop	lab conditions). Once stimulated, the three cells inflate rapidly,
plants and cause disease in our livestock.	severely constricting the nematode. Over a period of 24-36
	hours the interior of the nematode is completely filled with
It should come as no surprise that such a successful group	hyphae and then digested from the inside out.
of organisms is also a quarry of fungi. Nematophagous fungi
are found among the chytrids, zygomycetes, ascomycetes, and
		 To the mycologist, the nematode
basidiomycetes (the latter including the oyster mushrooms,		nooses of Arthrobotrysspecies are an
	Last roundup	evolutionary wonder, while to the farmer
Pleurotusspp.). The specialized toxins and mechanisms to
	Death comes swiftly	it’s a thing of beauty. To the plant
trap, kill, and ingest nematodes are as diverse as the fungi	for an unsuspecting	pathogenic nematode it’s the last thing
	soil nematode moving	it will ever see. Lasso Fungi are being
themselves. Some, such as Pleurotus, produce short branches	among a tangle of	studied and commercially deployed as
	plant rootlets and	an environmentally benign way to

tipped with toxins that kill their prey on contact, while

fungal hyphae.

defeat a very serious pest.

others produce conidia that are ingested by or stick to the

nematodes as they swim past—upon germination the host

Fungal hyphae

Nematode

is soon filled with fungal hyphae. There are also species that produce swimming zoospores that are chemically attracted to nematodes, hunting them down and attaching to them, usually around an orifice.

However, perhaps the most studied nematophagous fungi are species of the genus Arthrobotrys, the Lasso Fungi. The hyphae of Arthrobotrysgrow through the soil like most other molds, but set nematode traps along the way. Some species of

FUNGI & HUMANS

AMANITA MUSCARIA

European

	SCIENTIFIC NAME	Amanita muscaria
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Fly Agaric
	FAMILY	Amanitaceae
	HABITAT	Forest and urban
Invasive species

The Fly Agaric mushroom is without doubt the most	Scientists have determined recently that the European
recognizable mushroom on the planet. Whenever	Fly Agaric is an aggressive invasive fungus, and is spreading
a mushroom is needed for an illustration, postcard,	all over the world; Amanita muscariais now found in Australia
cartoon—even emojis—this handsome red mushroom	and New Zealand, Argentina, Brazil, Chile, and Tanzania.
with its white scales is depicted. This is a big	This mycorrhizal symbiont of trees seems to be moving
mushroom, often with a cap that can be 12 inches	around with pine and Eucalyptus plantation stock, and has
(30 cm) in diameter, on top of a stalk that is maybe	recently made its way to North America—populations have
inches (30 cm) or more tall, with a scaly bulbous base.	been detected in Alaska, California, and Massachusetts.
	Although this is potentially good news to the lumber
The Fly Agaric is known from all continents except	industry, as this mushroom promotes the growth of plantation
Antarctica, although not all populations are quite the same.	trees outside of their native range, it doesn’t seem to stay put
The current scientific understanding is that there are multiple	and is jumping to native species in its new home. In North
subspecies (or varieties) of Amanita muscaria. The original	America it is now regularly found growing in stands of native
description came from the red variety of Europe and Asia, but	birch trees, and it is unclear what this means for the future of
there is a different red variety in western North America, and	forests. Many people fear the invasive European Fly Agaric
eastern North America has a yellow variant. However, even	may outcompete the native mycorrhizal fungi that could
those colors aren’t absolute; the red varieties can range from	currently be key components in a healthy ecosystem.

red to orange to yellow to cream, and it’s the same for the yellow varieties, which can also drift across the color spectrum.

 The archetypal mushroom,

Amanita muscaria.

FUNGI & HUMANS

LENTINULA EDODES

Cultivated

	SCIENTIFIC NAME	Lentinula edodes
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Mushrooms
	FAMILY	Omphalotaceae
	HABITAT	Forest
Domesticated mushrooms

For centuries people the world over have been growing	mushrooms are such vigorous saprobes that you can simply
mushrooms right along with their fruits, vegetables,	collect their fruitbodies and some of the substrate they are
and livestock, but the trend for growing edible	growing in, and introduce that into similar substrates at your
mushrooms at home has gone mainstream in recent	home. A compost pile, mulched flower bed, bale of straw, or
years. It’s easy to see why, and hard to think of	even freshly cut logs can support mushrooms you have
anything more rewarding or sustainable, considering	collected from the wild, just as long as it is not already fully
you can use lawn and other cellulosic wastes, some	colonized by other competing fungi. One very important
kitchen scraps, or even newspaper and cardboard	word of caution, though: never consume any plant or
waste as a growing medium.	mushroom without being absolutely certain of its identity.

Many wild plants and mushrooms are deadly. Of course, mushrooms that are mycorrhizal partners of trees and other plants cannot be cultivated, but many saprobic wild

mushrooms that are found in fields and woodlands over most

Shiitake cultivation

 Fully mature Shiitake mushrooms

ready to harvest. The mushrooms are

Shiitake mushrooms have of the globe have been successfully domesticated, including

named for the Japanese words for oak

long been grown on oak

Blewits, Wine Cap Stropharias, field mushrooms, and oyster

logs, their natural

and mushroom, shiiand take.

substrate. Nowadays it’s

mushrooms. Other species, such as Shiitake and Nameko,

become commonplace to

which were once curious exotic mushrooms in restaurants, grow them on “synthetic” logs. The “log” illustrated

here, started out as bag of are now commonplace on grocer’s shelves. Even if you don’t

moist hardwood sawdust

enjoy eating them, you can still get a lot of enjoyment from

inoculated with Lentinula

cultivating mushrooms—they’re fun to observe, beautiful to edodes. After several weeks the fungus will

photograph (a great subject for time-lapse photography!), and

permeate through the

those fungi are always at work for you, creating rich soil from entire substrate, digesting

and binding it together

wastes that you might otherwise send off to the landfill.

into a solid mass. Once

removed from the bag,

Mushroom cultivation has become so popular that you

the log will erupt in

can find many sources of “spawn,” which is the starting point beautiful—and savory—

Shiitake mushrooms.

of mushroom cultivation (usually sawdust or grain, inoculated with a particular fungus). Most flower and vegetable seed catalogs now sell spawn, along with instructions on how to grow it, but it can be even easier than that. Many wild

FUNGI & HUMANS

PLEUROTUS NEBRODENSIS

Nebrodo Oyster

	SCIENTIFIC NAME	Pleurotus nebrodensis
	PHYLUM	Basidiomycota
	ORDER	Agaricales
Mushroom
	FAMILY	Pleurotaceae
	HABITAT	Forest
Endangered species

Like all life on the planet, fungi are at risk due to	As a result of these various stressors, Italian scientists
habitat loss and other pressures. Some critically	estimate that fewer than 250 fruitbodies now make it to
endangered organisms have been given Red List status	maturity and release spores each year, and this has led to their
in order to protect and monitor them, including the	Red List status. But there is reason for hope. In recent years,
oyster mushroom, Pleurotus nebrodensis. This species	the Italian mycologist Gianrico Vasquez has located
is considered critically endangered and thought to be	populations of this fungus on the mainland of Italy, so it
endemic to a small region of Nebrodo forests in	seems that the mushroom species may be more widespread
northern Sicily.	and common than previously thought; like many others, it
	may rarely be seen because it does not fruit that often, and
So why is this mushroom so rare? To start with, Sicily is an	not necessarily because it is “rare.” Additionally, clever
island, so its habitat was never huge and was always naturally	mushroom cultivators have figured out how to produce this
limited. Like many other places on the planet, that habitat	delicious mushroom in culture, so you never know—you may
has also become increasingly fragmented by agriculture and	soon find cultivated nebrodini bianco(as the Italians call it)
development, which has restricted the fungus even more. It is	coming to a market near you.

also something of a victim of its own success: the mushroom is delicious and highly prized, so no one can resist picking it, despite its protected status.

 Although it may be vanishing from the wild, the Nebrodo Oyster is now cultivated as seen here.

FUNGI &

THE FUTURE

FUNGI & THE FUTURE

Fungi that heal and feed

The majority of fungi go about their business unseen by us, but they are everywhere. Whether you realize you are doing it or not, you could not get through a single day without interacting with them, be it in the form of a pathogen, a medicine, a food, or something else entirely.

It doesn’t matter if you’re fascinated with fungi or	and some other grain are all screened to ensure this
grossed-out by them: we rely on them to do important	dangerous mold is not present. Although it is not fully
services for us and to produce innumerable products	understood why fungi excrete mycotoxins, scientists
that are essential in all our lives. While many molds	presume that it is either a way to subdue other
are not harmful, some produce powerful toxins called	competing microbes in their environments, or some
mycotoxins, which include unsavory sounding	form of chemical communication between like species
catabolites, such as patulin, ochratoxin, vomitoxin, and	that just so happens to be toxic to other life.
trichothecenes. Aflatoxin, which is produced by the	Yet while these toxins have the power to harm us,
fungus Aspergillus flavus, is the most carcinogenic	other antimicrobial compounds in fungi have been
substance naturally produced on Earth—corn, peanuts,	harnessed to improve our health and even save our

FUNGI THAT HEAL AND FEED

lives. Claviceps purpureamay be best known as the cause of ergotism (see page 88), but it possesses a particular compound that causes a constriction of blood vessels, which is used in drugs to treat vascular headaches. At the same time, lysergic acid diethylamide (LSD) and related compounds have long been investigated for psychiatric therapies, and this research is providing interesting results in the treatment of depression and

ر Aspergillusmolds can be

pathogenic; a biopsy of lung tissue

other illnesses.

reveals aspergillosis infection.

However, perhaps the most famous antibiotic— and one that has saved untold lives—is penicillin, a

× Conidiophore of an Aspergillus

species, a common source of

compound excreted by a species of Penicilliummold.

mycotoxins

The discovery of penicillin was purely serendipitous.

Indeed the fungus was a contaminant and should

ش Microscopic view of a Penicillium

species. Like Aspergillus, Penicillium

never have been in the lab in the first place. In 1928

species are common causes of food

Alexander Fleming noticed a mold growing among

spoilage around the home and

elsewhere.

a bacterial culture. As a microbiologist, he’d seen

س Penicilliumspecies growing in culture. These ubiquitous fungi can grow on a wide range of substrates.

ز Photo showing Penicilliumculture bottles and small ampules of penicillin drugs produced during World War II. Prior to the advent of antibiotics, infectious disease frequently killed more soldiers than combat.

FUNGI THAT HEAL AND FEED

contamination a million times, but this culture was	discoveries for humanity, Fleming, Chain, and Florey
different—there appeared to be a clear “halo”	shared a Nobel prize for the discovery.
surrounding the mold. The bacteria could grow to that	Many other fungal-derived antibiotics have since
zone but something in the culture medium prevented	been discovered, including cephalosporin and
them from getting any closer to the mold. Fleming	griseofulvin, and semisynthetic penicillins are also
reasoned that the fungus must be excreting something	common (methicillin, ampicillin, carbenicillin,
into the agar medium, so he searched for and isolated	amoxicillin, etc.). Antibiotics work in seemingly
the substance responsible, naming it penicillin.	miraculous ways because they target physiological
But it wasn't until 1940 that two other researchers,	pathways in bacteria that animals don’t possess, so they
Howard Florey and Ernst Chain, “rediscovered”	tend not to have any effect on human cells. However,
Fleming’s experimental notes and were able to create	their amazing utility has also led to over-use, and some
a stable form of penicillin that could be administered	bacteria have evolved resistance to these medicines,
orally to a sick patient. Although many other researchers	rendering them useless against a growing number
were involved in what has become one of the greatest	of pathogens.

FUNGI & THE FUTURE

FUNGI IN FOOD	process can be halted at this stage and the malt dried
As well as medicines, fungi are used to create all sorts	and roasted, ready for brewing; beer is made by
of fermented foods, beverages, and flavorings. As long as	fermenting malted grain.
there are simple sugars present, fungi can likely ferment	Because saké is made from grain (in this case rice)
them to alcohol, which is why fruit juices can be	it is also a beer, but making saké requires two fungi to
fermented to make wine (which in turn can be distilled	be added to cooked rice. The first, Aspergillus oryzae
to create brandy). However, unlike fruit, plants store	(also known as “koji mold”) produces copious amounts
sugars in grain as starch. This is not fermentable until	of amylase enzyme, which breaks down the rice starch
the grain germinates, at which point it creates amylase	to a fermentable sugar. Saccharomyces cerevisiae, a brewer’s
enzyme that converts the starch to sugar for use by the	yeast, is then used to carry out fermentation. Aspergillus
baby plant. In the brewing industry, the germination	oryzaeis a workhorse of Asian cuisine, and is used to

make miso, soy sauce, and vinegars, as well as countless other fermented bean pastes and sauces.

Another Aspergillusspecies, Aspergillus niger, is used to make multiple enzymes, including alpha-galactosidase,

which is useful for breaking down certain complex

س Walnuts contaminated with

sugars and is a component of dietary supplements that

Aspergillus oryzae. Molds in this genus

are well known for growing on all sorts

decrease flatulence. Aspergillus nigeris also used to make

of grain and nuts.

high-fructose corn syrup, but the most economically

ض Conidiophore of an Aspergillus

important product that comes from it is citric acid—

species used in the food and drug

industry to create many useful

a popular flavoring in many foods and soft drinks.

compounds.

Although citric acid can be derived from Citrusplants,

ز Aspergillus nigeris ubiquitous in

all life produces this six-carbon sugar as part of cellular

soil and causes “black mold,” which is

a common contaminant of food.

respiration, and it is far cheaper and easier to grow any

FUNGI & THE FUTURE

number of fungi that excrete citric acid as part of their	to clean up oil spills, whereas Hormoconis resinae(also
metabolism. Of these fungi, Aspergillus nigeris the most	known as Amorphotheca resinae) has a bad reputation for
efficient, as it is able to use cheap carbohydrates as a	breaking down all manner of hydrocarbons. Commonly
starting point and convert up to 95 percent (by weight)	known as the Kerosene Fungus, Hormoconis resinaeis
of the sugar substrate into citric acid.	found in nature, but is more often encountered in fuels
	(jet fuels, diesel, petroleum, you name it), where it
FUNGI IN INDUSTRY	removes alkanes and water, playing havoc with engines.
In industry, fungi can be something of a double-edged	Kerosene Fungus can also be found in wood that has
sword. There are species that can degrade synthetic	been treated with creosote, as can the mushroom
materials such as plastics, petroleum, and toxic chemical	known ominously as the Train Wrecker (Neolentinus
waste, but these fungi can be harmful or advantageous	lepideus). However, while the Train Wrecker is
depending on when, where, and what they are feeding	frequently seen rotting treated wood—including
on. Oyster mushrooms, for example, make positive	wooden railroad ties (railway sleepers)—there is no
news headlines when they are deployed in the attempt	evidence to confirm its involvement in train disasters.

FUNGI THAT HEAL AND FEED

ز The Train Wrecker, Neolentinus lepideus, can make use of wood that is unsuitable as a substrate for most other fungi, including wood that has been treated with preservatives or standing timber following a forest fire as in this photograph.

ش Looking like a bouquet of flowers, this pink variety of oyster mushroom is as beautiful as it is delicious.

FUNGI & THE FUTURE

Fungi that kill

For millennia, peoples from all over the world have foraged or cultivated mushrooms for food, fiber, and medicine. Often, the knowledge of what was safe and edible—and in some cases cultivable—was kept “locally” and passed down orally as part of tradition and culture. But that is not always the case.

We know that the Indigenous peoples of North America and Australia had their own ethnomycological and ethnobotanical knowledge, but many of the immigrants who made their way to these places lost this knowledge at some point, or simply didn’t gain it to start with. This perhaps explains in part why there are plenty of “mycophobes” to be found in the world, with attitudes ranging from suspicion to outright fear, or accepting fungi as food, but only as a single variety, usually purchased off the shelf in a can.

However, a revolution is underway, and mushrooms are increasingly being seen as cool, exciting, and tasty. Consumer tastes and demands have switched from sad, wilted button mushrooms to “exotic” cultivated mushrooms, such as Shiitake, oysters, cremini, and portabella. Consumers have also started to move away from factory farmed vegetables (including mushrooms) toward organically grown produce, perhaps even growing it themselves. Of course, with mushrooms there is also the option to get back to nature and head into woodlands to forage for fungi yourself. Whichever

ز A wide array of mushroom

colors and shapes awaits right outside your door!

path you take, mushrooms—both wild-foraged and	-95 percent of allthe mushroom-poisoning fatalities
cultivated—are now seen not just as a source of	in the world. Yet while there is no way to diminish
nutrition, but also as a source of healthful, indeed	the reputation of this group, there are many
medicinal, properties.	misconceptions held about it. For a start, the vast
	majority of Amanitaspecies are not toxic at all (many,
TOXIC KILLERS	such as the Caesars, are highly prized edibles), while
Alongside a dramatic increase in people foraging wild	other groups that produce certain toxic compounds
mushrooms for food, we are—perhaps unsurprisingly—	are not considered deadly.
seeing an uptick in the number of mushroom poisonings	In fact, there are just a few deadly species of the
that are occurring around the world. It is therefore	genus, all of which belong to a single closely related
imperative that anyone interested in foraging for wild	group (section Phalloideae). This group includes Amanita
mushrooms educates themselves first, because while	phalloides(the infamous Death Cap) and species known
there are comparatively few dangerous species, people	as Destroying Angels—the latter are aptly named, as
die every year from eating the “wrong” mushrooms.	their striking, pure white appearance belies their deadly
Although there are several disparate groups of	reputation. Members of the Phalloideaeproduce
poisonous mushrooms, one group in particular should	amatoxins (also called amanitins), and these are the
be discussed: the Amanitamushrooms. These are the	compounds that poison us and other mammals.
most notorious mushrooms, and are responsible for	However, even though amatoxin-producing Amanitas

FUNGI THAT KILL

Some wild mushrooms are poisonous

A number of wild mushroom species are poisonous—some deadly—and these species may closely resemble popular edible species. The most infamous mushroom toxins are amatoxins, orellanine, gyromitrin, muscimol, and muscarine.

False Morel

Fool's Funnel

Deadly Webcap

Fool's Webcap

N+

Muscimol

H H

N+

Gyromitrin (Toxin can be

reduced through cooking

Amatoxins

but still dangerous)

Muscarine

(a-amanitin shown)

Orellanine

Fly Agaric

Panther Cap

Destroying Angel

Death Cap

ص Depictions of poisonous mushrooms have been featured in books about mushrooms since long ago. Shown (far left) is a color plate from Edible & Poisonous Mushroomsby Mordecai Cooke, published in 1894. Cooke was a well-known 19th-century Victorian expert on British mushrooms.

ص Beautiful but deadly, the

Destroying Angel is a species of Amanita.

س Unassuming but deadly, tiny

can lead to death, our perception of how lethal they

Funeral Bells (Galerinaspp.) produce

are is probably inflated. Worldwide, amatoxin mushroom

amatoxins just like the much better

known Amanitaspecies.

poisoning is fatal about 50 percent of the time, but

in North America and Europe, where swift medical treatment is usually available, the fatality rate may be as low as 10 percent. Be warned, though: survivors often suffer from permanent organ damage, so do not push your luck!

Amatoxins work by blocking the functionality of the enzyme RNA polymerase II, which is responsible for the transcription of DNA into messenger RNA (mRNA). As this is the first step within cells for the production of proteins, it means the function of organs is affected, along with cell division; if protein synthesis is stopped, cell death soon follows.

FUNGI THAT KILL

GRISLY STAGES OF AMATOXIN POISONING

One of the alarming aspects of amatoxin poisoning in humans is that many victims have no indication that they are in any danger. The mushrooms do not have a foul or bitter taste (indeed, some taste quite pleasant), they have no off-putting smell, and there is no immediate indication of gastric distress. The symptoms of amatoxin poisoning typically don’t start to show until 6-24 hours after ingestion, by which time the toxins have been absorbed completely by the body and four stages of poisoning ensue:

Stage 1: After an initial state of gastric distress

(vomiting and diarrhea), the patient appears to recover. During this “latency period” the toxins are actively destroying the victim’s kidneys and liver, even though the victim experiences no discomfort.

Stage 2: As they enter the second stage of

poisoning the victim experiences chills, severe abdominal cramps, violent vomiting, and bloody diarrhea.

Stage 3: The victim seems to recover again, at which point a severe case of food poisoning may be suspected and, assuming they’ve been hospitalized,

Once ingested, the toxins first reach the liver,

the patient may be sent home.

which—among other duties—functions to detoxify blood. Because blood circulates the toxin repeatedly to

Stage 4:	This is when the real problems begin for
the liver, this is the organ that is usually impacted the
	the victim. The fourth stage is a relapse,
most. The damage to the liver can be so profound that	occurring 3-6 days later. Kidney and
it often masks the effects on other organs, but	liver failure often occur, leading to death.
postmortem studies of animal and human subjects have	Patients may also die from internal
revealed cellular damage in the kidneys, pancreas,	bleeding due to the destruction of clotting

factors in the blood.

adrenal glands, and testes. Interestingly, non-mammalian RNA polymerase enzymes are either unaffected or affected only slightly. Some mammals are much less sensitive to amatoxins than others, depending on the uptake of the toxins into the blood system from the GI track: humans and guinea pigs are most sensitive; dogs are 10 times less sensitive; and cats are less sensitive still.

FUNGI & THE FUTURE

Magic mushrooms

One other group of fungi that deserves attention (and is possibly the hottest area of mycology of late) is the psychedelic groups of fungi; the so-called “magic mushrooms.” Prior to 1957, few people had heard mention of the small, nondescript fruitbodies of an obscure genus of fungi called Psilocybe. That all changed on May 13, 1957, with an article published in Lifemagazine by ethnomycologist and corporate vice president R. Gordon Wasson.

MAGIC MUSHROOMS

Wasson’s article, “Seeking the Magic Mushroom,” was a personal account of mystical ceremonies and the ritual use of hallucinogenic mushrooms in southern Mexico, accompanied by dark, grainy photographs. Prior to its publication, Wasson and his Russian-born wife, Valentina, had spent four summers in the remote mountains of southern Mexico seeking the mushrooms with vision-giving powers. On Wasson’s last odyssey he was accompanied by Professor Roger Heim, a mycologist and head of France’s Muséum National d’History Naturells, who collected and named many of the magic mushroom species used in the sacred rituals.

However, no one knew what drug was present in the mushrooms until 1958, when Albert Hofmann— a Swiss chemist working for Sandoz Pharmaceuticals— isolated and synthesized the two principal active

ر Psilocybe cubensis, a psychedelic

species, in cultivation.

ingredients, which he named psilocybin and psilocin.

FATHER OF ETHNOBOTANY

Wasson and his associates were not alone in traveling to Mexico to learn about the ancient mushroom rituals of the Indian peoples. At around the same time, the renowned Harvard ethnobotanist, Richard Evans Schultes, traveled to the region to collect any and all potentially psychotropic plants. Schultes documented the use of psilocybin mushrooms in shamanic ceremonies by Indigenous Mesoamerican peoples and discovered evidence of “mushroom cults” documented in ancient writings. He also found artifacts including “mushroom stones” that were revered by shamans and hidden from suppression by the colonials. Here we see Schultes in Amazonia, circa 1940.

FUNGI & THE FUTURE

Magic mushrooms

On Wasson’s last trip to Mexico, he was accompanied by renowned mycologist Roger Heim. In Mexico, Heim was able to study and illustrate the mushrooms in their habitat. Life published Heim’s life-size watercolor paintings and they are reproduced here, along with the scientific names given at the time.

Conocybe siligineoides

Psilocybe aztecorum

Psilocybe caerulescens nigripes Psilocybe caerulescens mazatecorum

Psilocybe zapotecorum

Psilocybe mexicana

Stropharia cubensis

MAGIC MUSHROOMS

ز Timothy Leary and Laura Huxley, widow of author Aldous Huxley.

Hofmann was no stranger to the hallucinogenic properties of fungi. In 1938 he synthesized lysergic acid diethylamide (LSD-25), which is isolated from the fungus Claviceps purpurea(Ergot), and it was this fascination with hallucinogens that led him to investigate Psilocybespecies.

Curiously, America’s Central Intelligence Agency (CIA) also traveled to Mexico with Wasson to discover magic mushrooms, although Wasson was unaware of their presence at the time. Prior to his third fieldtrip,

Wasson had received a handwritten letter purporting	Leary felt that the mind-altering mushrooms could
to be from a graduate student called James Moore, who	be the ideal instrument for enabling a therapist to reach
wanted to study magic mushrooms. Moore claimed	the mental state of the disturbed, and within six weeks
he had been awarded a grant through a research	of his return from Cuernavaca, Sandoz Pharmaceuticals
foundation, which he said he would use to help fund	had granted Leary four bottles of purified psilocybin
Wasson’s expedition if he could travel with him. Wasson	pills for his research. Along with a colleague, Richard
agreed to take Moore to Mexico, not realizing that	Alpert (who later changed his name to Ram Dass), and
both the money and Moore were coming from the	several graduate students, Leary started to experiment
CIA. Moore’s subsequent collection of mushrooms	with the effects of different dosages of the hallucinogen.
became part of an ongoing CIA mind control program	To escape the sterility of academia Leary’s
known as Project MK-Ultra, headed by the infamous	experiments soon moved from the classroom to his
chemist and spymaster, Sidney Gottlieb.	home and to student residences, and undergraduates
Intrigued by Wasson’s Lifearticle, many other	began to hear rumors of psilocybin sessions turning
people found their way to the region in subsequent	into orgies. The rumors also reached traditional
years. In the summer of 1960, Dr. Timothy Leary was	psychologists at Harvard, and their displeasure soon
vacationing in Cuernavaca when he tried mushrooms	found its way into the pages of the Harvard Crimson.
purchased from a street peddler. As a psychotherapist	When Leary started including mescaline and LSD in
and newly appointed director of the Center for	his experiments the faculty decided he had gone too
Research in Personality at Harvard University, Leary	far, and in 1963 both Leary and Alpert were fired.
felt that the mushrooms could form the basis for his	By then, though, young people around the world
newly proposed existential approach to psychotherapy,	were smoking pot and exploring all manner of
which centered on the therapist becoming immersed in	hallucinogenic drugs: the Summer of Love was
the patient’s psychological turmoil.	just around the corner.

FUNGI & THE FUTURE

Extreme fungi

There is really nowhere on Earth you can go where fungi do not dominate or at the very least colonize. Terrestrial environments are the main realms of fungi, of course, but there are also those that are adapted to more extreme habitats.

Wherever temperate moist climates favor life, fungi are obvious, with showy mushrooms erupting from soil and rotting wood. In the steamy, drippy tropics fungi and lichens cover every surface (and each other), but they can be found in much drier parts of the world as well. Although they may remain underground for years, or even centuries, they are present in the Great Plains of North America, the Mediterranean, the scorching interior of Australia, and even California’s Death Valley, just doing what they need to do to survive. Perhaps more surprisingly, the perpetually frozen and windswept rocky coast of Antarctica features fungi. In fact, besides marine birds, fungi dominatelife in this extreme environment, although it is unlikely you’ll see them unless you know how to look.

DESERT FUNGI

In deserts, fungi are there year in, year out, but many of them rarely emerge to form fruitbodies. If desert mushrooms do show themselves, it will happen after an infrequent precipitation event, and will be accompanied

ز An expanse of desert just south

of Bagdad, Iraq seems like the last place you would expect to find fungi but Terfeziaspecies fruit following winter rains. These prized desert truffles command a high price in the markets throughout the Middle East.

EXTREME FUNGI

FUNGI & THE FUTURE

by the presence of mycophiles looking to check them	below). Although many of these mushrooms are of the
off their “life list,” like birdwatchers seeking out rare	gilled sort, their gills never fully form and their caps
birds. Yet while they are rare and feature interesting	never open, as this would subject the delicate gills and
adaptations that enable them to live in an arid	hymenial surface to instant drying. Desert fungi include
environment, these strange mushrooms are not much to	Battarrea, Podaxis, and Tulastomaspecies, which are well
look at. Indeed, as a result of evolutionary pressure they	known in arid habitats of Australia, North America, and
all mostly look the same: sort of a closed puffball-like	Europe, as well as desert truffles such as Terfeziaand
cap on a long stalk, which is often very deeply rooted	Termaniaspecies (although these remain underground
in the soil (presumably arising from a moist zone deep	for their entire lives, even during fruiting).

Soil crust fungi are more common than mushrooms in arid regions, but they are just as cryptic and we are only now beginning to understand how important they are to their ecosystems. Many soil crust fungi are in fact tiny lichens that bind together and stabilize soil, and

even fix nitrogen from the atmosphere, adding critical

س When rains fall in desert habitats,

nutrients to arid soils. Desert biocrusts are easily

Podaxisspecies, somewhat resembling

Shaggy Mane mushrooms, emerge.	damaged by disturbance from livestock and recreational
ض Another peculiar desert mushroom	vehicles and grow back extremely slowly.

is Battarrea phalloideswhich curiously produces spores from atop its cap, rather than underneath.

ENDOLITHIC FUNGI	within the Antarctic landscape’s exposed porous rocks.
Perhaps the last place on Earth that you would look for	Colonies of endolithic fungi can be distinguished by
fungi is Antarctica. Without question, this is the most	differently colored bands within the rock: a black band
difficult habitat for fungi—indeed all of life—to eek	consists of melanized lichen and non-lichenized fungi
out an existence. Not only is it perpetually cold, dry,	(the melanin protects against the intense UV radiation),
and windy, but most of the year it is completely dark.	below which you may find a green layer, comprised of
This darkness is punctuated by a summer period when	non-lichenized photosynthetic algae and cyanobacteria.
it is light around the clock, with intense UV radiation	This bizarre form of life was completely unknown
due to the thin atmosphere and ozone layer. But here,	until the 1980s, but endolithic fungi are now seen as a
just as everywhere else on the planet, fungi have figured	curiously important subject of study. Why? Because it
out a way to live, somewhere between the limit of	has been postulated that the Antarctic conditions—
adaptability and near-death, barely surviving and rarely	extremely low temperatures, rapid evaporation, and
reproducing.	high solar irradiation—may resemble those of early Mars.

There is not much in the way of sustenance for a saprobe to live on, but coprophilous fungi have adapted to life on the wastes of marine birds. Most fungal life comes in the form of lichens, though, and these are the

region’s dominant primary producers. As life under

س Dung-loving fungi (coprophilous

fungi). In Antarctica this fungi has

Antarctic conditions is exceptionally tough, the lichens

adapted to the extreme conditions

have become endolithic—that is, they exist (amazingly)

by feeding on marine bird droppings.

FUNGI & THE FUTURE

TUBER MELANOSPORUM

Périgord Truffle

	SCIENTIFIC NAME	Tuber melanosporum
Most prized	PHYLUM	Ascomycota
	ORDER	Pezizales
	FAMILY	Tuberaceae
	HABITAT	Forest

While many species of truffles are collected	or sexy. The chemical most responsible for this is
commercially around the world, the Périgord Black	,4-dithiapentane, which is synthesized and used in the food
Truffle (Tuber melanosporum) of France and the	industry to create all sorts of “truffle-flavored” oils and other
Piedmont White Truffle (Tuber magnatum) of Italy	foodstuffs. It is also used by counterfeiters, who not only mix
dominate the market. Demand for these truffles	cheaper truffle species into batches of Périgords to increase
far exceeds supply and wild-collected yields are	their weight, but also adulterate them with synthetic aromas.
notoriously unpredictable, which enables them to	Such is the scale (and cost) of this problem that biologists are
command prices of around US$610-2,130 per pound	working to create a complete genome of the Périgord truffle
(US$1,345-4,700 per kg).	fungus, which they hope will lead to rapid tests that can

determine the authenticity of all truffles at the time of sale. Everyone always asks: If they’re so difficult to find in

the wild, why not cultivate them? The problem is, truffle

 Slicing open a truffle fruitbody

cultivation is notoriously difficult, in part due to its

reveals the dark convoluted hymenium,

clandestine underground lifecycle. Truffle fungi are

or spore-producing surface inside.

The hymenium will be covered with asci.

mycorrhizal symbionts; Tuber melanosporumand Tuber magnatumlive on the roots of oak (Quercusspp.) and hazelnut trees (Corylus avellana). Their hyphae extend outward in

all directions and if they fuse with another of their kind,	Next generation of truffles
a fruitbody may result. Ascospores are produced in the	Truffles are underground

fruitbodies produced by

fruitbodies, but as these remain underground they have to certain fungi. The fruitbody is odiferous and nutritious, thus

rely on animals for dispersal. Mycophagous animals, including

enticing to a number of

wild boars and rodents, dig up and eat the truffles, passing the mammals. The main purpose for this sort of a mushroom is,

spores through their digestive tract and dispersing them with of course, reproduction. Within the truffle are asci,

their feces.

chambers that house the

The key to the truffle’s success is odor. Components

spiky-looking ascospores.

Wherever they are deposited

of their aroma are irresistible mimics of mammalian sex

in the forest, the spores will

pheromones, and this not only helps mammals locate them germinate and may take up residence on the roots of host

by smell, but also makes them irresistible to humans, with an trees, starting a new

generation of truffle fungus.

aroma that is variously described as earthy, garlicky, musky,

FUNGI & THE FUTURE

MORCHELLA SPP.

Burn Morels

	SCIENTIFIC NAME	Morchellaspp
Enigmatic mushroom	PHYLUM	Ascomycota
	ORDER	Pezizales
	FAMILY	Morchellaceae
	HABITAT	Forest and alpine

Besides truffles, no wild mushrooms are as highly	why not simply cultivate them? The answer has always been
prized for their culinary value as morels, and none are	the same: because it is impossible! Many have tried for a long,
as enigmatic, have so much lore, or have been bragged	long time. Some experiments on commercial morel farms
(and lied) about as much. All continents except	in Alabama and Michigan yielded results temporarily but
Antarctica have morel species, and where there are	eventually failed to be sustainable. However, there seems to
morels, there are impassioned pickers who guard the	have been a breakthrough only recently!
secret spots where these springtime gems are collected.	It turns out, some of the morel species that fruit from
	disturbed areas or burns (e.g., Morchella importuna) can be
Yet as elusive as the black and yellow morel species are, there	domesticated. Zhu Douxi, Head of Mianyang Edible Fungi
is one morel that is even more enigmatic: the mysterious	Research Institute of Sichuan in China, is a pioneer in the
Burn Morel or Fire Morel. Its common name comes from	mycological world and known as “The Father of Morels”
the fact that this morel only fruits in the spring following a	in China. He is the first person in the world to successfully
forest fire. Although the mycelium is known in habitats that	cultivate morels outdoors. His morel cultivation technique,
haven’t burned, something changes when a fire comes	which took him 27 years to develop, involves cultivation in
through, and in the first spring that follows, the charred	buried nutrient bags under shaded terraces. Furthermore his
barren forest will be carpeted with an eruption of morels that	methods are now being replicated in at least 20 countries
has to be seen to be believed. Researchers have postulated	from Europe to North Africa, as well as Asia.

that changes in soil pH, salinity, or the release of nutrients after a fire somehow stimulates the mycelium to fruit, or that maybe the fire changes the soil biology, chemistry, or microbial competitors following the fire event, but no one knows for sure.

So wherever there is a forest fire event, circle that place on your map and wait. Come spring, the Burn Morels will return to sporulate, but you will need to be quick—it only lasts for a few weeks, and then they go back into hiding, awaiting the next big burn.

 The first sign of spring: a Burn

For centuries people have searched long and hard (often

Morel emerges one year after a

in vain) for elusive morel mushrooms. I get asked all the time:

wildfire in Montana.

FUNGI & THE FUTURE

AMANITA PHALLOIDES

Death Cap

	SCIENTIFIC NAME	Amanita phalloides
Most infamous	PHYLUM	Basidiomycota
	ORDER	Agaricales
	FAMILY	Amanitaceae
	HABITAT	Forest and urban

Amanita phalloidesis one of the most widespread	organisms in nature display aposematic or “warning” colors,
mushroom species in the world; although the Death	such as red and yellow, fungi do not follow these rules. In
Cap was first described from Europe, it is now known	fact, the most commonly encountered poisonous mushrooms
from all continents except Antarctica. We also know	are drab brown or gray, and many are pure white.
more about its ecology than most other mushrooms,	Furthermore, most taste quite pleasant, so there’s nothing to
because wherever it turns up, death soon follows.	warn you that what you’re currently savoring in a prepared
As mentioned previously, this mushroom is responsible	dish is about to kill you.

for the majority of mushroom poisoning deaths worldwide, and experts predict that the number of poisonings from Death Cap mushrooms will continue to rise.

That Amanita phalloidesis now so widespread is attributed to its ability to pair up with a wide assortment of host trees, including horticultural and economically important nut, lumber, and pulpwood species. This has enabled it to be transported and transplanted globally; in North America, the Death Cap’s range has expanded dramatically in just a few decades and there is no reason to think that it won’t continue to grow.

If you are at all interested in collecting wild mushrooms for food, it is essential that you familiarize yourself with all of the deadly Amanitamushroom species. Dangerous mushrooms, including Death Caps, often resemble other familiar edible mushrooms, including some cultivated species.

Unfamiliar pickers erroneously assume that poisonous

 The most infamous mushroom on

mushrooms will warn of impending danger with garish

the planet is the Death Cap, Amanita

phalloides. This mushroom is

colors, foul odors, or a bitter or off-putting taste, but this

responsible for 90-95% of all

is not necessarily the case. While most toxic or venomous

mushroom fatalities globally.

FUNGI & THE FUTURE

PSILOCYBE CUBENSIS

Magic Mushrooms

	SCIENTIFIC NAME	Psilocybe cubensis
Amazing chemistry	PHYLUM	Basidiomycota
	ORDER	Agaricales
	FAMILY	Hymenogastraceae
	HABITAT	Forest and urban

Psilocybeis a large genus (nearly 400 species	seems to function in a similar way, but it disrupts the
worldwide) of small brown mushrooms that grow on	information coming from the sensory organs, and it is this
decaying wood or the dung of mammals. No doubt due	disruption that causes hallucinations.
to its ease of cultivation, the best-known species of the	Psychedelics produce an atypical state of consciousness
group, Psilocybe cubensis, is native to the Caribbean	that is characterized by altered perception, cognition, and
and Gulf of Mexico region. Other notable species	mood. It has long been recognized that these compounds
include Psilocybe tampanensis, a producer of tuber-	might have therapeutic potential for neuropsychiatric
like underground sclerotia (sold in parts of Europe	disorders such as depression, obsessive-compulsive disorder,
as “magic truffles”); Psilocybe weraroa (of Oceania	and addiction. Indeed, psilocybin and psilocin were used to
including Australia); and Psilocybe semilanceata,	successfully treat tens of thousands of patients in the 1950s
known as the Liberty Cap, a native of northern Europe	and 60s, and have recently returned to the forefront of
but nowadays commonly found on lawns and pastures	research. Among psychedelics, psilocybin has been shown to
around the world.	rapidly relieve the symptoms of depression, with sustained

benefits lasting for several months after just a single dose of

What makes Psilocybeso “magic” is that these mushrooms

the drug.

contain the psychotropic tryptamine compound psilocybin (or its analogs, psilocin or baeocystin). With the exception of the spores, all parts of the mushroom contain the compound, and once ingested the psilocybin is rapidly turned into psilocin inside the body. Structurally, psilocybin and psilocin both resemble the neurotransmitter serotonin, and as a result they bind with and activate serotonin receptors in the brain. It is not completely understood how psilocin—and serotonin—works in the brain, but serotonin is thought to play an important role in integrating information coming in from all the sensory organs (eyes, ears, nose, etc.). Psilocin

 Psilocybe cubensismushrooms

contain psychotropic compounds in every part of the fruitbody except the spores.

FUNGI & THE FUTURE

LACCOCEPHALUM MYLITTAE

Stonemaker

	SCIENTIFIC NAME	Laccocephalum mylittae
	PHYLUM	Basidiomycota
	ORDER	Polyporales
Fungus
	FAMILY	Polyporaceae
	HABITAT	Forest
Elusive mushrooms

One of the strangest mushrooms of Australia is also the	The sclerotia of Laccocephalum mylittaeare thought to
country’s most reclusive. In fact, the sclerotium of the	be perfectly happy growing underground for many years,
fungus—typically a very large tuberous mass—is more	possibly even decades, and there are documented examples
often encountered than the actual fruitbodies. The	of fruiting taking place indoors several years after they have
Reverend Miles Berkeley first placed this fungus in the	been collected from the forest. The sclerotia can grow to
genus Mylitta, as he thought it was a truffle, but when	massive sizes—between 10 and 20 pounds (4.5-9 kg) is not
H. T. Tisdall displayed one with emergent mushrooms at	unusual—and besides storage, these structures may also be
a Field Naturalists’ Club in Victoria in 1885, the fungus	an adaption to life in fire-prone habitats. Certainly, wildfire
was determined to be a terrestrial stalked polypore.	seems to be the catalyst for mushroom formation. Following
	the massive bushfires in Australia in 2019, mushrooms of
Currently named Laccocephalum mylittae, this saprobic fungus	Laccocephalumwere commonly seen emerging in areas
occurs in the rainforests and Eucalyptusforests of south and	where the fungus was previously unknown. One species,
eastern Australia; at least two other related species are known	Laccocephalum tumulosum, is even known as the Phoenix
from other habitats and regions of Australia. Early written	Stonemaker, due to its habit of rising from post-fire ashes.

accounts all state that indigenous Australians regarded the excavated sclerotium as a delicacy, which was probably sliced and eaten raw (leading to it being referred to as “native bread”). This is unusual, because while many fungi produce hard sclerotia, most likely for the storage of nutrition prior to reproduction, only a few of these have been collected as food by humans. In the Northern Hemisphere we know that Wolfiporia extensa(“tuckahoe”) was consumed by Native Americans, but Polyporus tuberaster—a polypore similar to Laccocephalum—is not eaten (although this may be because, in addition to resembling a stone, the interior often accumulates

stones and other debris, hence it sometimes being called the

 The enigmatic Laccocephalum

“stone mushroom”).

mylittae. True to its name, this fungus

can produce mushrooms from a stone-like sclerotium even after it has been excavated.

FUNGI & THE FUTURE

GEOPYXIS CARBONARIA

Bonfire Cups

	SCIENTIFIC NAME	Geopyxis carbonaria
Amazing ecology	PHYLUM	Ascomycota
	ORDER	Pezizales
	FAMILY	Pyronemataceae
	HABITAT	Forest and alpine

Consecutive years of unprecedented fires in many	fire and are an indicator that Burn Morel fruitings are
parts of the world—notably Australia and North	imminent. This mushroom is well known from all over the
America—have enabled one particular group of poorly	globe—from Australia to North America, and pretty much all
known and rarely seen fungi to be studied in greater	places in between—and although the recently burned ground
detail. This group is the pyrophilous fungi, which show	may be carpeted with this fungus, they pretty much only
up almost exclusively following fire. As with the Burn	show during that first post-fire year. After that they go back
Morel (see page **) heat is certainly a factor in	into hiding, going about their lives as an important symbiont
breaking the dormancy of the spores and sclerotium	of the forest, waiting for the next big fire to signal them to
in many species of fire fungi. Fire also results in a	spring into action.

dramatically increased soil alkalinity (a higher pH) and a reduction in competition from other microbes in the soil, which helps the fungi as well. But where are these enigmatic fungi in the intervening years, and what are they doing?

The answer, it turns out, is that many of these fungi live as endophytes within lichens, mosses, bryophytes, and other plants (including trees) in fire-prone areas. Most pyrophilous fungi are ascomycetes, as is the case with most of the lichen fungi, although a few are basidiomycetes, including some species of Pholiota. This is interesting to note, as this genus is better known for its saprobic species; wherever you find rotting wood, Pholiotas are likely to be found as well. But not the pyrophilous species of the genus—they seem to be endophytes of bryophytes.

Possibly the most beautiful of all pyrophilous fungi is Geopyxis carbonaria. Known as Bonfire Cups and Pixie Cups (among many other names), these fairly large, stalked cups

 Bonfire cups are often the first life

will appear in profusion in the early spring following a forest

to emerge from the ashes of wildfires.

GLOSSARY

anamorph The asexual state or	aseptate Lacking septa, often	ectomycorrhiza (often called “EcM
form of a fungus. Compare with	pertaining to the hyphae seen in	fungi”), mycorrhiza in which
teleomorph.	zygomycetes (also see coenocytic).	fungal hyphae grow around the
		root and between cells of the
arbuscular mycorrhiza (often called	basidiocarp A fruitbody bearing	epidermis.
“AM fungi”), a mycorrhizal fungus	basidia and basidiospores.
that lives as a symbiont of plant		facultative Optional, an adjective
roots; its hyphae grows into and	basidiomycetes A group of fungi	referring to a biological attribute
penetrates the cortical cells, but not	that reproduce sexually by	or way of life, such as a method
the cellular membrane, of its plant	producing basidiospores from	of feeding, locomotion, deriving
host and produce absorptive	a basidium.	energy, reproduction or association.
structures called arbuscules.		Thus an organism may be a
	basidiospore A haploid spore	facultative carnivore, anaerobe,
arbuscules Intricately branched	produced on a basidium following	aerobe, parasite or symbiont; the
haustoria of arbuscular mycorrhizal	karyogamy and meiosis.	opposite of obligate.
fungi, they are considered the
major site of exchange between the	basidium (pl. basidia) A club-shaped	fruitbody Also termed “mushroom,”
fungus and host; so named for they	chamber that produces basidiospores;	it is the sexual spore producing
look like “little trees.”	basidia are characteristic of the	structure of ascomycete or
	Basidiomycota.	basidiomycete fungi. Authors may
ascocarp A fruitbody containing		also say “fruit body” or “fruiting
asci and ascospores.	catabolism The breakdown of	body.”
	complex molecules in living
ascomycetes A group of fungi	organisms to form simpler ones,	fungi imperfecti An informal
that reproduce sexually by the	together with the release of energy.	and polyphyletic grouping of
endogenous formation of		unrelated fungi that are known
ascospores in an ascus.	coprophilous Growing in or	only by their anamorphic
	on dung.	(asexually reproducing) forms.
ascomycetous Referring to the		Many of these are the anamorphs
ascomycetes.	diploid A nucleus containing the	of ascomycetes and basidiomycetes,
	complete set of chromosomes (2n)	but without sexual fruitbodies their
ascospore A haploid spore	from the fusion of 2 nuclei from	affinities remain obscure.
produced within an ascus following	different, but sexually compatible
karyogamy and meiosis.	haploid hyphae, each having only	gills The lamellae, or gill-like
	one half (n) the diploid number	hymenial structures of agaric
ascus (pl. asci) A sac-like chamber	of chromosomes.	mushrooms.

that produces ascospores; asci are characteristic of the Ascomycota.

GLOSSARY

gleba The inner mass of spore-	hymenophore Structure bearing		mitosis The process in eucaryotic
bearing tissue of gasteroid fungi	the hymenium, the mushroom.	cells by which the chromosomes
like puffballs, earthstars, and		contained in a nucleus are first
stinkhorns; in the latter group, the	hypha (pl. hyphae) A single filament		replicated and then separated into
gleba is a gelatinous and foul-	of a fungus.		two identical copies of the original
smelling goo on the surface of cap.		set, one of each set going to a
	karyogamy The fusion of two	daughter nucleus.
haploid The number of	haploid nuclei within a dikaryon
chromosomes (n) in a gamete,	to form a diploid zygote; compare	monokaryon A fungal spore or
which is half the diploid number	with plasmogamy.	hyphal cell containing only one
(2n) in a zygote. The haploid stage		haploid nucleus.
predominates in the life cycle of	lichen A composite organism
most fungi. During the sexual	consisting of a symbiotic		mycelium (pl. mycelia) The mass of
phase two compatible nuclei fuse	association between a fungus (the		hyphae making up the thallus of a
(karyogamy) to form a diploid	mycobiont), which forms the	fungus.
zygote, meiosis soon follows,	thallus of the lichen, and either
resulting in haploid spores that	a photosynthetic alga or a		mycosis Fungal disease of humans.
produce new haploid hyphae.	cyanobacterium (the photobiont),
	or both. The morphology and	nonseptate Lacking septa; also
haustorium (pl. haustoria) A	physiology of the lichen is quite	termed “aseptate.”
specialized appendage of a parasitic	different from that of either
fungus that penetrates the host’s	symbiont living alone.	obligate	“Of necessity,” an adjective
tissues, but does not penetrate the			referring to a biological attribute
host’s cell membranes; haustoria	meiosis The process by which a	or way of life, such as a method
of arbuscular fungi are called	diploid (2n) set of chromosomes	of feeding, locomotion, deriving
“arbuscules.”	in eucaryotic organisms are first		energy, reproduction or association.
	replicated (4n), then undergo	Thus an organism may be an
heterothallic A fungus that requires	a reduction division	obligate carnivore, anaerobe,
two compatible mating types for	(2 ´ 2n), and then a second		aerobe, or symbiont; the opposite
sexual reproduction to occur.	reduction to produce	of facultative.
	haploid (n) gametes or spores.
homothallic A fungus that is			photobiont The photosynthesizing
self-fertile.	mycobiont The thallus-producing	algal or cyanobacterial partner in
	fungal partner in the symbiotic		the symbiotic associations known
hymenium The fertile tissue giving	associations known as lichens.	as lichens.

rise to and bearing the sexual spores (e.g., the gills or agarics and the pores of boletes and polypores).

GLOSSARY

plasmogamy The cytoplasmic	taxonomic Adjective referring
fusion of two compatible hyphal	to the classification and/or
cells.	nomenclature of an organism
	or group of organisms.
rhizomorph A mycelial strand of
aggregated parallel hyphae attached	taxonomy The discipline devoted
to the basal portion of some	to the collection, cataloguing,
mushrooms.	classification and naming of
organisms.
saprobe A saprobic organism,
typically a fungus or bacterium.	teleomorph The sexual stage of a
saprobic Obtaining nourishment	fungus. Compare with anamorph.
from dead or decaying organisms.
	zygospores A thick-walled sexual
saprotrophic Adjective describing	spore formed by the fusion of two
an organism that feeds on dead	similar gametangia; characteristic
organic matter.	of the zygomycetes.

sclerotium (pl. sclerotia) A highly condensed mass of undifferentiated sterile (asexual) hyphae typically encased in a hard, woody, thick, dark rind. These structures enable those fungi producing them to survive under adverse

environmental conditions.

septum (pl. septa) A “partition,” or cross-wall in a hypha, cell, or spore.

sterigma (pl. sterigmata) A small narrow stalk-like structure at the apex of a basidium upon which a basidiospore forms.

 Vibrant golden Laetiporus sulphureusfound in southeastern

stroma (pl. stromata) A compact

Michigan, USA. This highly prized

edible polypore is commonly known

mass of fungal tissue on or within

as Chicken of the Woods due to its

which fruitbodies develop.

texture and flavor.

GLOSSARY

USEFUL RESOURCES

RECOMMENDED BOOKS ABOUT FUNGAL SCIENCE, TOXINS, HISTORY, LORE, AND THE IDENTIFICATION OF MUSHROOMS

Ainsworth, G.C. 1976. Introduction to the History of	Laessّe, T., and J.H. Petersen. 2019. Fungi of Temperate
Mycology.Cambridge University Press, Cambridge;	Europe.Princeton University Press, New Jersey; 1708
pp.	pp.
Alexopoulos, C.J., C.W. Mims, and M.M. Blackwell.	Letcher, A. 2007. Shroom: A Cultural History of the Magic
. Introductory Mycology, 4th edition. Wiley, New	Mushroom.Harper Collins, NewYork; 360 pp.

York; 869 pp.

Lincoff, G. 1981. National Audubon Society Field Guide to

Arora, D. 1986. Mushrooms Demystified: A Comprehensive

Mushrooms.Knopf, NewYork; 926 pp.

Guide to the Fleshy Fungi, 2nd edition.Ten Speed Press,

Marley, G.A. 2010. Chanterelle Dreams, Amanita Berkeley; 959 pp.

Nightmares.Chelsea Green Publishing,Vermont; 255 pp. Benjamin, D.R. 1995. Mushrooms: Poisons and Panaceas.

McIlvaine, C. 1900. One Thousand American Fungi. W.H. Freeman and Company, NewYork; 422 pp.

Bobbs-Merrill Company, Indianapolis; 749 pp. Boughler, N.L., and K. Syme. 1998. Fungi of Southern

Millman, L. 2019. Fungipedia: A Brief Compendium of Australia.University of Western Australia Press,

Mushroom Lore.Princeton University Press, New Jersey; Nedlands, WA, Australia; 391 pp.

200 pp.

, B.A., and T. Lynch. 2020. The Beginner’s Guide

Money, N.P. 2011. Mushroom. Oxford University Press, to Mushrooms: EverythingYou Need to Know, from Foraging

NewYork; 201 pp.

to Cultivation.Quarry Books, Beverly, MA; 160 pages.

Petersen, J.H. 2012. The Kingdom of Fungi. Princeton Bunyard, B.A., and J. Justice. 2020. Amanitas of North

University Press, New Jersey; 265 pp.

America. The FUNGI Press, Batavia, Illinois; 336 pages.

Phillips, R. 2010. Mushrooms and Other Fungi of North Dugan, F.M. 2008. Fungi in the AncientWorld: How

America.Firefly Books, NewYork; 319 pp. Mushrooms, Mildews, Molds, andYeast Shaped the Early

Ramsbottom, J. 1953. Mushrooms & Toadstools: A Study of Civilizations of Europe, the Mediterranean, and the Near

the Activities of Fungi.Collins, London; 306 pp. East. APS Press, St. Paul; 140 pp.

Harding, P. 2008. Mushroom Miscellany.Collins, London;	Rolfe, R.T., and F.W. Rolfe. 1925. The Romance of the
pp.	FungusWorld: An Account of Fungus Life in Its Numerous

Guises, Both Real and Imaginary.Lippincott Co., Hudler, G.W. 1998. Magical Mushrooms, Mischievous

Philadelphia; 308 pp.

Molds.Princeton University Press, New Jersey; 248 pp.

Schaechter, E. 1997. In the Company of Mushrooms. Kendrick, B. 1992. The Fifth Kingdom.Focus Publishing,

Harvard University Press; 296 pp.

Newburyport, MA; 386 pp.

Taylor, T.N., M. Krings, and E.L. Taylor. 2015. Fossil Fungi.Academic Press, London; 382 pp. Webster, J., and R. Weber. 2007. Introduction to Fungi, 3rd edition. Cambridge University Press, Cambridge; 841 pp.

USEFUL RESOURCES

ORGANIZATIONS AND WEBSITES DEDICATED TO THE EDUCATION AND CONSERVATION OF FUNGI

Associazione Micologica Bresadola

ambbresadola.it

Australasian Mycological Society

australasianmycologicalsociety.com

European mushroom information

fungus.org.uk

European Mycological Association

euromould.org

Fungal Network of New Zealand and New Zealand Mycological Society

funnz.org.nz

Fungi Magazine

fungimag.com

Fungi of California

mykoweb.com

Index Fungorum

indexfungorum.org

Mushroom Expert

mushroomexpert.com

Mushroom Observer

mushroomobserver.org

Mushroom Growers’ Newsletter

mushroomcompany.com

North American Mycological Association

namyco.org

 Enokitake (or simply enoki) is a popular cultivated mushroom in Japanese cuisine. This mushroom (Flammulina velutipes) also grows in the wild and is an important wood rot fungus.

INDEX

A			B		Burn Morels 217		common stalked polypore 36
					butt rots 104, 117		conidia 50, 96, 119, 234
actin 36			ballistospory 32-3
							Conifer Maze Conk 202-3
Agaricus 106				Bamboo Stinkhorn 54-5	C
						Contarinia 50
Ajellomyces 112			basidia 22, 32, 33
					Caesar’s Mushroom 158-9		convergent evolution 14, 85,
	alcohol 78-83, 162, 232			basidiomycetes 14, 16, 18, 22,
					Candida albicans 112	, 198
Amanita 76				-9, 90-1, 106, 119, 124-5,
					carbon crisis 210-13		Coprinites dominicana 17
	Amanita caesarea 158-9			-9, 158-9, 164-7, 194-5,
					carbon fixation 102		coprophilous fungi 41, 62,
	Amanita muscaria 229, 236-7			-9, 202-5, 230-1,
					carnivorous fungi 12	-7
	Amanita phalloides 150, 229		-41
					Caterpillar Fungus 92-3		coral bleaching 136
amatoxins 76				bioluminescence 72
					Cedar Apple Rust 121		Corn Smut 124-5
amber 16-17			butt infections 117
					cell walls 12		Corpse Finder 109
	ambrosia beetles 46, 175			farming 175, 177, 178
					cellulase 101, 178, 181, 224		Creolophus cirrhatus 220
	amphibian decline 138-9, 228			lichens 191, 200
					cellulose 12, 46, 102-3, 106,		Cronartium ribicola 120-1
anastomosis 24			post-fire 217
					, 178, 181, 198, 224	Crown Rust 119
	ants 85, 175, 177, 198, 226			spore release 31, 32-3, 40
					Cerrena unicolor 194-5		Cryphonectria hypovirus 24
	Apple Scab 117-19			Batrachochytrium dendrobatidis
					CharlesVI, Holy Roman		Cryphonectria parasitica 24, 136,
	appressorium 115		-9
					Emperor 150
	Aquatic Mushroom 58-9			bats 138, 140-1, 228
					Cheilymenia coprinaria 106	Cryptococcus 69
	arbuscular mycorrhizas 183,			Beech Orange Fungus 122-3
					chempedak tree 50	Cryptococcus gattii	-5
-11, 213				Beetle Hangers 196-7
					Chestnut Blight 24-5, 141		Cultivated Mushrooms 238-9
	Archaeomarasmius legettii 17		berry truffles 60
					chitin 12		Curvularia protuberata 25
	Armillaria 68, 72, 117		biocontrols 226
					Chlorociboria 70		cyanobacteria 191-2
	Armillaria mellea 74			biodiversity 136, 184, 208,
					Chlorociboria aeruginascens	Cyttaria 80
Arthrobotrys 226			-20
					-3	Cyttaria gunnii	-3
	Arthrobotrys dactyloides	-5	biofuels 224, 225
					Choanephora 50
	Artillery Fungus 56-7			bioluminescence 72-5		D
					chytridiomycetes 18, 21, 116,
Artocarpus 50				biotrophs 101, 110, 114-15,
					-9	Daldinia 104
	ascomycetes 14, 16, 18, 22, 48,		, 179
					chytridiomycosis 138-9	dandruff 112
	-1, 84, 86-9, 92-5, 104,		Birch Polypore 90
					cicadas 96		Darwin, Charles 54, 80, 122
	, 110, 116, 118-19,			bird’s nest fungi 40-1
					Cladosporium 69		Darwin, Henrietta 54
	-3, 126-7, 130-3, 143,			Black Bolete 178-9
					Claudius Caesar 150, 158		Death Cap 150, 229
	, 160-1, 168-9, 196-7,			black mold 22, 107, 232
					Claviceps purpurea 48, 88-9,		dermatophytes 110-12
	-1, 215, 232-5		Blastomyces 112
							deuteromycetes (imperfect
	biofuels 225		Blewit 104
					ClementVII, Pope 150		fungi) 18, 21
	lichens 191, 200			boletes 178-9, 204-5
					climate change 139, 166,		Dichanthelium lanuginosum 25
	spore release 31			Bordeaux Mixture 162
					-20, 228	Disciseda 40
	temperature 69			“botryticized” wines 232
					Clitocybe nuda 104	discomycetes 50
ascus 22, 31, 119			Botrytis cinerea	-3
					club fungi seebasidiomycetes		Downy Mildew of Grape
	Ash Bolete 204-5			bracket fungi 35, 104
					Coccidioides 112	-3
Aspergillus				brewing yeasts 78-83
					coevolution 122, 174, 177, 178	Draculaorchid 51
	Aspergillus sydowii 136			brown rot fungi 103, 104
					coffee 152-3		Dry Rot Fungus 230-1
	atomic radiation 69			Bryoria fremontii 200-1
					Coffee Rust 152-3		Dutch Elm Disease 25, 142-5
	Auriscalpium vulgare 104			Bryoria tortuosa 200-1

commensalism 101, 172

autotrophs 69

Buisman, Christine 143

common jelly fungus 24 Buller’s drop 32-3

INDEX

E		fossil record 16-17, 106-7,	Hesperomyces virescens 196-7	L
		, 181	Heterobasidion annosum 226
earpick fungus 104				Laboulbeniales 196
		La France Disease 24	heteroecious fungi 119
ectomycorrhizal fungi 9, 17,				Lasso Fungi 234-5
		Fries, Elias Magnus 168	heterotrophs 12, 101
				lawns 106, 128
		fruitbodies 14, 30-3, 36, 40,	Histoplasma 112
ectozoochory 43-4				leaves 104-6
		-4, 50, 54, 58-62	honey mushrooms 68
edible fungi 9, 104, 158, 182				Lentinula edodes 36, 103, 238-9
		Aquatic Mushroom 58	honeydew 107, 179
Black Bolete 178				lichens 69, 172, 188-93,
		Cyttaria 80	Horn Stalkball 126-7
Corn Smut 124				-1
		Onygena 126	Horsehair Lichens 200-1
Cultivated Mushrooms				lignin 102-3
		Termitomyces 198	Humboldt, Alexander von 72
-9				ligninolysis 74-5
		fungicides 118, 156, 157, 162	hymenium 31, 32, 33, 35
Cyttaria 80				Little Brown Bats 140-1
		funiculus 41	hyphae 36
Lobster Mushroom 130-1				living fossils	, 191
		Fusarium graminearum 94-5	funiculus 41
St. George’s Mushroom				Lobster Mushroom 130-1
			plant parasites 115
	G			Lophodermium pinastri 86-7,
			stromata 48
Titan Mushroom 198
	galls	, 178-9, 204	Hypocreales 84-5, 88, 92, 94,
Emerald Ash Borer 204				luciferin 74
		Ganoderma 69, 160	, 160

Emerging Threat 164-5

gasteroids 40-1

hypogeous fungi 43

endangered species 215,

Geopyxis carbonaria 217

Hypomyces lactifluorum 130-1

218-20

hypovirulence 25, 141

Malassezia 112

ghost moths 92

fungi 182-3

Marasmius crinis-equi 104 Ghost Pipes 187

endophytes 6, 8, 25, 48, 60, 86,

Marasmius oreades 106, 128-9 Ghoul Fungus 109

92, 184, 217

marine environments 16, 136,

Giant Horntail wasp 178

imperfect fungi see

endozoochory 43

164

gilled mushrooms 35, 58, 198,

deuteromycetes

entomopathic species 84-5

Massospora cicadina 85, 96-7

insects 43-6, 48, 50, 74

Entomophthorales 84-5

meadow mushrooms 106

glomalin 210-11, 213

ambrosia beetles 46, 175

Epichloë elymi 48

medicine 76, 78, 92, 193, 218

glomeralean fungi 22

ants 85, 175, 177, 198, 226

epiparasitism 187

Megacollybia 117

Golden Oyster mushroom

Aquatic Mushroom 58

epiphytic fungi 8, 50, 184, 226

melanins 68-70

farming 46, 175-9, 198

epiphytotics 119

Meselson, Matthew 94

gravitropism 35-6

honeydew 107

ergot fungi 49, 76, 88-9, 150

Metarhyzium acridum 226

Great Famine 136, 138, 154

”mind control” 84-5

ergotism 49, 88, 150

Metarhyzium anisopliae 225,

green algae 191-2

Mossy Maze Polypore 194

Eryniopsis lampyridium 85

226

Green Stain 132-3

mutualisms 174-5

European Fly Agaric 236-7

microfungi 69

	Gymnosporangium juniperi-		stinkhorns 54
					Microsporidia 21
F	virginianae			termites 175, 176, 177, 198
						Millardet, Pierre Marie Alexis
	Gypsy Moth 117			wood-boring 46, 101, 178
Fairy Ring Mushroom 128-9
		Gyrodon merulioides 204-5	invasive species 228-9
fairy rings 106, 128					mimicry 48-51, 60
			ionizing radiation 69
False Turkey Tail 24	H				”mind control” 67, 84-5
farming of fungi 46, 175-9,			J		monecious fungi 119
	Hartig net 182
					Monilinia fructicola
	Hat Thrower 22, 62-3		Janzen, Dan
field mushrooms 106						Monilinia vaccinii-corymbosi 50

heart rot 104, 226

Flammulina 36

Morchella 142

Hebeloma aminophilum 109

Fly Agaric 236-7

morels 142, 217

Hebeloma radicosum 109

keratin 109, 110, 126

Flying Saltshaker Fungus 96-7

Mossy Maze Polypore 194-5

Hebeloma syrjense 109 Fomes fomentarius 70, 90-1

INDEX

mutualism 12, 22, 24-5, 48,		Paracelsus 76			polypore fungi 36, 70, 90-1,		Sagara, Naohiko 109
, 170-205		Paracoccidioides		, 104, 117, 194			St. Anthony’s fire 48, 49
mycangia 46		parasites 12, 98-133, 187		Polyporus brumalis 36			St. George’s Mushroom 166-7
mycelial network 184-5			of animals 21, 110-13	Porodaedalea pini 202-3			Salem Witch trials 88, 150
Mycena 72, 75		coevolution 174			Potato Late Blight 136, 138,		saprobes 12, 24, 54, 90, 98-133,
mycoheterotrophs 187		of fungi 24		-7		, 181
mycorrhizae 6, 8, 17, 180-7			of plants 21, 114-21	prions 24			sarcophilous fungi 109
	arbuscular 183, 210-11, 213		pathogens 12, 24-5, 46, 48, 50,		Protomycena electra 17		Scarlet Berry Truffle 60-1
Mycotoxin Producer 94-5			, 86, 90, 101, 112, 185,	Psathyrella aquatica	-9		Schwarz, Marie Beatrice “Bea”
mycotoxins 21, 88, 94, 200		, 226			pseudoflowers 48, 50, 52, 115
mycowood instruments 71			of humans 110, 112		Pseudogymnoascusdestructans	sclerotia	, 88
		melanins 68, 69		-1		sea fans 136
N
			“mind control” 67, 84-5		pseudopollination 48, 52		Serpula lacrymans 230-1
Nebrodo Oyster Mushroom		pandemics 134-69			pseudosclerotial plates 70		shelf fungi 14, 104, 160, 202
-1		of plants 114-21			Puccinia coronata avenae 119		shiitake mushrooms 36, 103,
Nectriopsis violacea	-9	Paurocotylis pila	-1	Puccinia graminis tritici	-20	, 238
Needle Cast Fungus 86-7		Peck, Charles Horton 85		Puccinia monoica 52-3			Slime Mold Eater 168-9
nematophagous fungi 234		Penicillium 69		puffballs 33, 40		smuts 119, 124-5
Noble, David 147, 149		peridioles 40-1, 56		pyrophilous fungi 217		sooty molds 107
Noble Rot Fungus 232-3		Phallales seestinkhorns				spermatia 48, 52
				R
Nothofagus 79, 80, 122		Phallus indusiatus 54-5					Sphaerobolus stellatus	-7
Nylander, William 192			Phanerochaete chrysosporium 103	radiation 69		Spilocaea pomi 119
		Phlebia gigantea 226		Reagan, Ronald 94		sporangia 62
O			Phlebopus portentosus 178-9				Spore Eater 160-1

Reboleira, Ana Sofia 196

PhoenicaulisRust 52-3

Red List species 220, 240

spores 30-63, 69, 74, 75

Omphalotus 72

phoenicoid fungi 217

Red Ring Rot 202

sporidia 124

Onygena 109

Pholiota highlandensis 217

reproduction 28-63, 67

sporocarps 43

Onygena corvina 126

phototropism 36, 62

respiration 102

Sporophagomyces chrysostomus

Onygena equina 126-7

Physisporinus vitreus 71

resupinate fungi 44

-1

Onygenales 109, 110, 126

Phytophthora 138

rhizoids 138

Sporormiella 106-7

oomycetes 145, 154, 162

Phytophthora cinnamomi 149

rhizomorphs 68, 72, 104, 106,

Sporothrix schenckii 112

Ophiocordyceps sinensis 92-3

Phytophthora infestans 154-7

Spribille, Toby 200

Ophiocordyceps unilateralis 85

Phytophthora ramorum 145, 147

Rhizopus stolonifer 22

Stereum 24

Ophiostoma ulmi 25, 143-5

Pilobolus 41

rhizosphere 210

sterigma 32

orchids 51, 187

Pilobolus crystallinus

, 62-3

ringworm 110

stinkhorns 40, 44, 54-5

otoliths 36

	Piptoporus betulinus 90		rose handler’s disease 112	Stradivarius violins 71
ضtzi the cadaver 90
	plants	rosetting 115		Sudden Oak Death (SOD)
Oyster Mushroom 240-1
	epiparasites 187	Russula 130		, 147
P	growth regulators 115	rusts	-3, 119-21, 152-3	summit disease 85
	mutualisms 180-7			symbiosis 101, 170-205
paclitaxel 184
	parasites 114-21	S		arbuscular mycorrhizas 210
Palaeoagaricites antiquus
	Plasmopara viticola 162-3			Choanephora 50
		sac fungi seeascomycetes
pandemics 134-69
	Pleurotus nebrodensis 240-1			insects 46
		Saccharomyces cerevisiae	-9

Pandora formicae 85

Pُldmaa, Kadri 160

Massospora cicadina 96

Saccharomyces eubayanus 79 Panellus 72

pollination 48, 50, 51, 124 Saccharomyces pastorianus 78-9

Panellus stipticus

INDEX

T wine industry 83, 162, 232

Witch’s Butter 24

teliospores 124

Wollemi Pine 148-9 termites 175, 176, 177, 198

wood 101-4

Termitomyces 177

Chestnut Blight 141 Termitomyces titanicus 198-9

Conifer Maze Conk 202 thermotolerance 25

Cryphonectria parasitica 136 thrush 112

Dry Rot Fungus 230 Tinder Polypore 90-1

Dutch Elm Disease 25, Titan Mushroom 198-9

142-5

Tokay wines 83, 232

Green Stain 132

Tomentella sublilacina 44

insect farmers 46, 177, 178 tooth fungus 220

ligninolysis 74-5

toxins 21, 76-83, 88, 94, 200

mosaic forests 216

Candida albicans 112

Mossy Maze Polypore 194 Mycotoxin Producer 94

spalting 70, 90

Tremella 24

Sudden Oak Death 145, 147 Trichoderma harzianum 226 wood-boring insects 46, 101,

Trichoderma reesei 224

178

Tricholoma gambosa 166-7

wood-wide web 185, 187 trichothecenes 94

truffles

, 43, 60

U Xylaria 104

Xylaria longipes 71

Down Puffball 40

xylophagous insects 46 Ustilago maydis 124-5

yeast 78-83

Vasquez, Gianrico 240

yellow morels 142

Venturia inaequalis 117-19

Vietnam War 94

violins 71

Zasmidium cellare 83, 232 viruses 24-5

zombification 67, 85

W	zoochory 42-7, 60

zoospores 21, 116, 138-9, 154 Westerdijk, Johanna 143

zygomycetes 18, 22, 50, 62, 84, Wheat Stem Rust 119

White Pine Blister Rust

120-1

white rot fungi 74-5, 90,

103-4, 178

White-nose Syndrome (WNS)

140-1

wildfires 213-17 Wine Cellar Mold 83

ACKNOWLEDGMENTS

This book is a very personal one. Besides being a collection Science Photo Library; p131: Kevin Oke; p133: Hakan Soderholm; p137 (bottom): Colin Munro; p138 (right): Nature Picture Library; p144: Andrew

of facts that you are likely to read in many other mycological

Hasson; p145: Inga Spence; p147: Ashley Cooper pics; p152 (bottom):

resources, it is also a compendium of my personal favorite stories

danaan andrew; p153 (top): Tribune Content Agency LLC; p157 (top):

about fungi from all over the planet. Some of these, doubtless, will Science History Images; p157 (bottom): Glasshouse Images; p167: Roger Philips; p180: Emmanuel LATTES; p183 (top): Scenics & Science; p186: Bill

be familiar to the educated mycophile. Many others are quite

Gozansky; pp192-193: Biosphoto; p195: Marina Sutormina; p199:

obscure and this book will likely be the only place you will see

imageBROKER; p201: Lee Rentz; p220: David Pressland; p227 (bottom):

them in print. I hope you enjoy reading about these fascinating	Custom Life Science Images; p250: Justin Long; p254 (left): Marcus
	Harrison - plants; pp262-263: REUTERS; p267: Hemis; p269: Randy
organisms as much as I have enjoyed writing about them.
Beacham; p275: Reading Room 2020.
I am indebted to the many educators and mentors who have	Science Photo Library:p20: Javier Aznar/Nature Picture Library; p21: Eye
influenced me throughout my life; it would take a great deal of	of Science; p31: Herve Conge, ISM; p63: Wim Van Egmond; p69: Dennis
	Kunkel Microscopy; p95: SCIMAT; p95 (inset): Keith Weller/US
space to thank them all and the publishers have been very strict
	Department of Agriculture; p139 (left): US Fisheries and Wildlife Service/
with me on word count. Thanks to the photographers who	Ryan Von Linden, New York Department of Environmental Conservation;
shared beautiful images of mushrooms and other fungi used in	p225: Dr Kari Lounatmaa; p235: Photo Researchers, Inc.
this book. Thanks also to the many authors of articles published	Nature Picture Library:p14: Guy Edwardes; p22: Guy Edwardes/2020VI-

SION; p24: John Waters; pp26-27: Andres M. Dominguez; p33: Niall

in Fungi Magazine over the years, some of which were catalysts

Benvie; p73: Juergen Freund; p173: Bence Mate.

for features in this book. And I would be remiss if I failed to

Nature in Stock:p2: Ronald Stiefelhagen; p84: Paul Bertner/Minden

thank Kate Shanahan, Natalia Price-Cabrera, and the entire	Pictures.
talented team of copy editors and illustrators at UniPress Books	Non-agency photographers:p17: Corentin C. Loron; p18, p114, p116,
for approaching me with the idea for this book, and their	p241: Britt A. Bunyard; p35: Joe McFarland; p59: Jonathan Frank; p61:

James & Dawn Langiewicz; p87: Carlos Cortés; p93: Daniel Winkler;

patience and tolerance with me during its completion.

p107 (top): Eric Smith; p127: Andrus Voitk; p161: Enrique Rubio; p169: Danny Newman.

PICTURE CREDITS

Creative Commons/Public Domain:p23: Public Domain/PD-US-expired;

The author and publisher gratefully acknowledge the permission granted	p44 (left): Gerhard Koller (CC BY-SA 3.0); p44 (right), p105: Alan
to reproduce the copyright material in this book.	Rockefeller (CC BY-SA 3.0); p48: Janet Graham (CC BY 2.0); 49 (left):

Sealox (CC BY-SA 4.0); p49 (right): Public Domain/PD-US-expired; p53: Shutterstock:p4 (top left): vilax; p4 (top right): valzan; p4 (bottom left):

Lesfreck (CC BY 3.0); p68: Stu’s images (CC BY-SA 3.0); p72 (bottom): bogdan ionescu; p4 (bottom right): Aksenova Natalya; p5 (top right):

xpixel; p5 (center right): Pisut chounyoo; p5 (bottom left): Shutter_arlulu; p5	Karin Mنrz/Public Domain; pp74-75: Jpallante (CC BY-SA 4.0); p78 (left):
(bottom right): lcrms; p7: CKHatten; pp8-9: Take Photo; pp10-11, p273:	Bob Blaylock (CC BY-SA 3.0); p78 (right): Public Domain/PD-US-expired;
Dmytro Tyshchenko; p12: mark higgins; p13: Protasov AN; p16: Matteo	p82: James Sowerby/PD-US-expired; p104: Paul Venter/Public Domian;
Chinellato; p30: Kichigin p34: epioxi; p38, p41, p227 (top), p277: Henri	p107 (bottom): Henk Monster (CC BY 3.0); p107 (inset): Michael
Koskinen; p39: Josep M Penalver Rufas; p57: weinkoetz; pp66-67: Denis	Koltzenburg (CC BY-SA 3.0); p109: Ben Mitchell/Wildeep/Public Domain;
Gavrilov Photo; p70: Melinda Fawver; p71 (top): Kimberly Boyles; p72	p112, p165, p244 (right): Nephron (CC BY-SA 3.0); p113 (bottom):
(top): Anne Powell; p77: Anita Kot; p79: Filip Fuxa; pp80-81: Pablo	Graham Beards (CC BY-SA 4.0); p118: Public Domain/The National

Merkel; p89: PHOTO FUN; p101: Sajjadabda; p103 (bottom):

Gallery, London; p121: Yue Jin/Public Domain; p125: Jamain (CC BY-SA LI CHAOSHU; p110: Pee Paew; p117: bogdan ionescu; p119: krolya25;

3.0); p138 (left): Dr Alex Hyatt, CSIRO (CC BY 3.0); p139 (right): Djspring p123: Ralf Broskvar; p137 (top): FtLaud; p137 (inset): Yayah-Ai; p142:

(CC BY-SA 3.0); p140: Vanvlitp (CC BY-SA 3.0); p141: Claudette Hoffman Ruth Swan; p152 (top): Platoo Fotography; p154, p247: Everett Collection;

(CC BY-SA 3.0); p142: Public Domain; p146: Akerbeltz (CC BY-SA 3.0); p159: Agorastos Papatsanis; p163: Somogyi Laszlo; p174: Michael Siluk;

p177: Zulashai; p179: MR.AUKID PHUMSIRICHAT; pp184-185: dugdax;	p149: Mary Ann Hansen (CC BY-SA 3.0); pp150-151: Baker, Joseph E/
p188: My September; p203: Henrik Larsson; p205: R. Croskery; p208:	Public Domain; p151 (inset): Dominique Jacquin/Public Domain; p153
Iva Hari; p213: Budimir Jevtic; pp214-215: James Percy; p216: Ryan	(inset): Smartse (CC BY-SA 3.0); p172: Public Domain; p178: Ryane Snow
McGill; p218: Favious; p219 (bottom): Chen Min Chun; p222: Susanne	(CC BY-SA 3.0); p183 (bottom): Rit Rajarshi (CC BY-SA 4.0); p190: Public
Leitgeb; p223: Matjaz Preseren; p224: Wingedbull; p226, p233: sruilk;	Domain/PD-US-expired; p191: Jason Hollinger (CC BY 2.0); p197: Gilles
p228: Kirsanov Valeriy Vladimirovich; p231: LariBat; p237: FotoLot; p239:	San Martin (CC BY-SA 2.0); p210, p211 (top): Keith Weller/USDA; p211
Trialist; p245: ChWeiss; p246: Kallayanee Naloka; p248 (left): Martina	(bottom): Sara Wright/USDA; p212: André-Ph. D. Picard (CC BY-SA 3.0);
Kachakova; p248 (right): Jirawan Muangnak; p249: Kateryna Kon;	p219 (top): Michael Hartwich (CC BY-SA 4.0); p221: Sasata (CC BY-SA

-153: Botanic Table of Elements; pp256-257: NK-55; p258:

3.0); p244 (left): CDC/Dr. Lucille K. Georg (PHIL #3964), 1955; p254 anitram; p261: Joseph Sohm; p264 (left): Dominic Gentilcore PhD; p265:

(right): Dan Molter (CC BY-SA 3.0); p259: Public Domain; p264 (right): Botond Horvath; pp280-281: Mary Elise Photography; p283: dan_nurgitz.

Doug Collins (CC BY-SA 3.0).

Alamy Stock Photo:p3, p271: Roger Phillips; p6, p25: Pat Canova;

Every effort has been made to trace copyright holders and to obtain their pp42-43: Henrik Larsson; p45: Naturepix; p47: fotototo; p50: 916

collection; p55: Malcolm Schuyl; p71 (bottom), p106, p129, p217: Henri	permission for the use of copyright material. The publisher apologizes for
Koskinen; p83: Panther Media GmbH; p91: Buiten-Beeld; p97: Nature	any errors or omissions in the above list and would be grateful if notified of
Picture Library; p100: Arterra Picture Library; p103 (top): INTERFOTO;	any corrections that should be incorporated in future reprints or editions of
p108: Tommi Syvنnperن; p111: Science Photo Library; p113 (top):	this book.

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