Some fungi make good lab pets. They’re agreeable, easy to grow fungi that eat simple, ordinary food: like potato or cornmeal extract with a dash of sugar. But my research focuses on fungi in the order Entomophthorales (featured in these previous posts). Most are obligate pathogens of insects— they can only complete their lifecycle on their host insect. Infection requires a spore shot from its host cadaver to fall onto an unsuspecting victim. Spores that fail can form a smaller, secondary version of themselves and shoot again if they don’t hit their bug the first time. Otherwise they die. Other spores form thick walls, and hunker down as resting spores designed to survive over the winter. These fungi are fascinating to look at, but make pretty poor pets.

While some fungi happily grow on wood shavings, or cigarette butts, or your leftovers, many have never been grown in culture. Examples include rust fungi, lichens, and Labouls. And consider mycorrhizal fungi, some of which need a whole tree to grow. When describing or experimenting on a species, researchers aim to do so in axenic culture, meaning the fungus is alone, without other living organisms. An axenic culture helps us analyze fungal biology without confounding factors. But due to the complexity introduced by obligate pathogenicity, some fungi remain impossible to culture axenically. Generations of mycologists have tried all kinds of crazy ingredients to entice all kinds of fungi to grow in the lab; we can’t always guess what they need. Only five years ago we learned arbuscular mycorrhizal fungi receive lipids from their plant hosts—perhaps this clue will help us culture them.⁴

Some fungi in the Entomophthorales prefer liquid media, like Grace’s Medium, in which they’ll grow in their protoplast stage. Protoplasts have shed their chitinous cell wall, usually after they break through the exoskeleton and arrive inside an insect. This allows them to evade the insect’s chitin receptors that recognize fungi and launch insect defenses. Under a microscope, in Grace’s medium, the living protoplasts gently twist and dance, movements induced by their internal cell skeleton.

Grace’s Medium mimics insect hemolymph, the bug equivalent of blood. This liquid medium is named after Thomas D.C. Grace, a pioneer of insect cell culturing.² Grace worked for over ten years, in labs across the world, to develop the first insect cell culture lines in 1962.³They are populations of cells isolated from an organism and grown in lab conditions, to facilitate research on, for example, ovarian or fat cells. The chemical composition of Grace’s Medium is similar to the nutrients insect-infecting fungi get from their hosts, and includes sugars such as trehalose, the primary sugar in hemolymph. Dr. Shang yin Gao developed a similar formula three years before Grace’s publication, but China’s cultural revolution delayed dissemination of his work and its recognition.⁶ Later in life, Grace used this worldwide renown to begin a peaceful life of farming in Australia.

Solid media for entomopathogenic fungi have proved equally challenging to develop. Some of best recipes, including one that involved Kellogg’s Special K cereal, are published in the “Manual of Techniques in Insect Pathology.”⁵ Development of nutrient-rich media to grow these fungi began in the 1950s and continues today.¹ Our favorite solid medium is SDAEYM (Sabourad’s Dextrose Agar Egg Yolk Medium). The main components are found at your local grocery store: yeast, whole milk, and egg yolks. It doesn’t mimic insect hemolymph as Grace and Gao’s media do. We call it Breakfast Medium, from the inevitable French toast smell that wafts across the lab once you cook it. On Breakfast medium, our favorite fungi spread over the dish as hyphae instead of protoplasts, which they do not do inside an insect

Grace called his culturing method “organized neglect,” as he simply switched out half the liquid medium for fresh medium each week or so, when the fungus was looking limp. A fungus needs new food after a while, same as you or I would after we finish a meal and go looking for the next one.  For fungi growing on solid media in Petri dishes, we cut out a small piece of the culture once it’s grown a while, and move it onto a new Petri dish of fresh media, where it grows some more (see our Taming the Fungus post). One problem with the Entomophthorales is that after some generations in culture they become quite unhappy, and will stop growing entirely. How and why they grow in such different forms under such varying conditions, we do not know.

It goes to show that even some things that seem most basic to research, like what your organism can eat, are still a great challenge in the world of fungi. But we do know that these bug-eating fungi enjoy “breakfast” in the morning, just like us.

Red-cockaded woodpecker at his nest, by M. Lammertink

Unfortunately, reliance on live trees has also proven to be this woodpecker’s downfall; human impacts, including logging and fire suppression, mean their ideal trees are rare. RCWOs need perfect “goldilocks” trees to flourish. These “just right” pines must be old and sturdy enough to support a cavity at the perfect height, yet not too old and overgrown that they hide predators. Their reliance on old-growth pine forests, now rare due to extensive logging, has left them federally endangered and teetering on the edge of extinction. But, in a conservation success, efforts to protect RCWOs have been fruitful. Relatively early recognition of their “goldilocks” needs led to measures protecting vital swaths of forest. In addition, fire management in key areas has helped keep the forest understory cleared and RCWO friendly.

This isn’t just good news for RCWOs—a host of other species rely on their cavities as well. When RCWOs move to a newer excavation in their cavity cluster, their abandoned holes are quickly occupied by birds and other critters who lack the energy or skill necessary to dig into a live tree themselves. This makes the RCWO a “keystone species,” like the wolves of Yellowstone or the sea otters of California’s kelp forests.
But why are these woodpeckers so adept at making holes in live trees? And why don’t all woodpeckers do that? That’s where our fungus friend enters the story.

Porodaedalea pini (=Phellinus pini) is a conk fungus that attacks the soft inner heartwood of conifers, causing a disease called Red Ring Rot or Red Heart. Spores can infect living trees via wounds and branch stubs, and the mycelium of this fungus grows in the wood, weakening the trees, and leaving them alive but worthless for commercial harvest. But where humans see a problem, the crafty RCWO finds opportunity. By targeting infected trees, RCWOs don’t need as much effort to carve out a cavity. But how do they know which trees are affected?

As it turns out, the RCWO, like many birds, can see beyond human vision, into the ultra-violet spectrum. A clever experimenter with a spectrophotometer found that wood infected with P. pini is visually distinct to the eyes of a RCWO—they can see the infection even when there are no conks. But RCWOs are very particular about where they place their nests. And despite being massively damaging to the lumber industry, P. pini is actually relatively rare in young trees. Even in the trees it does infect, it may not infect the most desirable spot for a RCWO cavity. So, do RCWOs wait patiently for P. pini to pop up in just the right spot? It seems like the answer may be no.

Red-cockaded woodpecker territory, image by M. Lammertink

Could the key to saving a rare bird be understanding its strange relationship with a fungus? Fostering this bird-fungus mutualism and finding a balance for timber companies and RCWOs may just make the difference in this bird’s fight for survival.

This isn’t the only story of a woodpecker and a fungus. In the western United States, the White-headed Woodpecker (Picoides albolarvatus) forages around the Veiled Polypore (Cryptoporus volvatus), feasting on insects attracted to the conk and spreading it in much the same way Porodadalea pini is spread. One can only wonder how many more bird-fungus relationships remain to be discovered.

A post by your editor, Kathie T. Hodge

Here’s a strange sight you might see while plying your canoe round the edges of a pond, or wading through a swamp. See how fresh and orange, how mysterious? This swelling on the stem of Swamp Loosestrife (Decodon verticillatus) is caused by a rust fungus called Puccinia minutissima. It’s covered the swollen stem with tiny fruiting bodies called aecia (say, “EE-see-ya”), and is busy cranking out itty bitty aeciospores.

Rust fungi are very host-specific. You don’t have to worry about them getting hangry and devouring the scenery. Puccinia minutissima attacks Swamp Loosestrife, and turns up its nose at all other plants except ONE. Aeciospores can’t even infect the plant they came from—they must be carried by wind to an entirely different species of plant, their primary host.

J.C. Arthur first described and named this rust back in 1907. But at that time, Dr. Arthur had NO IDEA it could infect Swamp Loosestrife — he’d seen it only on its primary host, the Slender Sedge Carex lasiocarpa, ON WHICH IT LOOKS DRAMATICALLY DIFFERENT. It took years to discover this connection. Today’s topic: How did we ever figure out the rust on Swamp Loosestrife and the rust on Slender Sedge are really the same fungus??

By way of background, I’ll tell you that rust fungi typically have five different stages (see below) and infect two different kinds of plants (they are heteroecious). There are exceptions, of course, but five and two is the strange rule of the rusts. This is what makes us all ask “how did this crazy system evolve?” and why students nervously ask, “is this on the exam?”

Rusts seem to specialize in baffling all of us. Here’s another seemingly unlikely pair: the fungus that causes Cedar Apple rust makes trouble on apple leaves, and also weird galls on eastern red cedar trees. Same fungus, different plants.

Let us now recite the five kinds of spores:

Spermatia act like pollen—they can fertilize a mate but can’t infect a plant.
Aeciospores can’t infect the plant they were produced on—they must infect a different kind of plant, the primary host.
The spores above are found on the alternate host; those below on the primary host.
Urediniospores are made in huge numbers on the primary host, and spread infection among plants of the same species, sparking epidemics.
Teliospores are made late in the season. They can’t infect a plant, but will wake next Spring to make…
Basidiospores are produced directly from teliospores in the Spring, and can infect only the alternate host.

Anton De Bary was the first to figure out the “two hosts” secret of the rusts, back in the 1860s. Working on Wheat Stem Rust, he found certain spores of wheat rust would NOT infect wheat. Taking a clue from farmers who knew that somehow wheat gets sicker when barberry bushes are near, in 1865 De Bary sowed those recalcitrant spores on barberry and Eureka! He discovered that barberry is the alternate host of the wheat rust fungus. Without both wheat and barberry, the fungus cannot complete its life cycle. Knowing this might help you manage the disease. This discovery is just one of the reasons we call De Bary a founding father of both Mycology and Plant Pathology.

High five, De Bary! That’s how you do it. Now back to J.C. Arthur. He was the first Botanist at the New York State Agriculture Experiment Station (now part of Cornell). His seminal work on fire blight showed that this destructive disease of apples and pears was caused by a bacteria. After earning his Doctor of Science at Cornell in 1886, he headed to Purdue University, where he bravely confronted the rusts.

At Purdue, Arthur discovered and named many rust fungi and studied their biology. Among his greatest contributions was to figure out their life cycles, finding and connecting a rust’s life stages on two plant hosts. This was an incredible enterprise. Rusts couldn’t be grown in petri dishes. To figure out how they spend their lives, one had to harvest aeciospores (Spring), or teliospores (Fall) from one plant and sow them on other suspects. Then wait and see.

Over three years, Canadian mycologist John Dearness sent Fall samples of rusted Slender Sedge from the shores of Lake Huron to Arthur in Indiana. For two Springs, Arthur’s assistants meticulously sowed the spores on all kinds of different plants that share a similar habitat. Nothing. Then a clue from a colleague in Michigan led them to try the spores on Swamp Loosestrife, which quickly and gloriously became infected. Success!

To give you a sense of how much work was involved in this effort to connect rust life cycles: Arthur reported that 2140 packets of spores were dispensed in over 3750 sowings. The plants had to be grown and monitored in greenhouses. The crew relied heavily on natural history observations of Arthur’s many collaborators to decide which plants to test. For two decades Arthur and a whole crew of young assistants labored over the North American rusts, naming them and connecting their life cycles. This, my friends, is how we know which rust life cycles require two kinds of plants, and which plants those are.

Rusts have simple, microscopic structures; they have sophisticated tastes in plants. There are over 7000 rust species. To identify a rust, one often needs to know what plant it’s on, and which of the five possible kinds of spores one is looking at. In this, Arthur’s enduring 1939 ‘Manual of Plant Rusts’ is still a standard text.

I don’t think the poor stinkhorn realizes just how polarizing it is. But it’s not hard to see why it produces strong, often visceral reactions. Just look at it. To be perfectly frank, what I see is a male sexual organ, dipped in excrement, with a mesh skirt. Some people (possibly focusing on the skirt) describe it as “amazing” and “beautiful,”¹ while others will only see it as “gross” or “scary,”² which probably explains why its common names range from the sweet-sounding “veiled lady” to the pragmatic “basket stinkhorn.” In professional circles, it’s known as Phallus indusiatus,³ where indusium (Latin for “outer tunic”) is the technical term for a kind of membrane and in this case refers to the skirt-like structure, and phallus… well, I suppose mycologists call it as they see it.

All in all, this is one mushroom that doesn’t look all that appetizing, and I haven’t even yet mentioned its number one cardinal sin: like any true stinkhorn, the thing stinks. Or, to be more precise, its cap is covered by a slimy, smelly, sticky substance called the gleba. The gleba stinks so bad that mycologist David Arora, in his Mushrooms Demystified field guide, devotes an entire paragraph to the various epithets people have used to describe the stinkhorn odor. Think “putrid” and “garbageous,” but also “like the damp earthy smell we meet with in some of our churches on Sundays.”⁴ Of course, that’s exactly how flies like it; they’re attracted to the rotten smell of the spore-containing gleba and inadvertently help the stinkhorn disperse its spores.

So the basket stinkhorn looks and smells bad. Surely then no one out there will be having stinkhorn stew for dinner. Hall et al., in their Edible and Poisonous Mushrooms of the World, agree (p. 247). Other sources, including Arora, point out that stinkhorns are edible, but only in egg stage: “the odorless stinkhorn ‘eggs’ are considered a delicacy in parts of China and Europe, where they are pickled raw and even sold in the markets (sometimes under the name ‘devil’s eggs’). Captain Charles McIlvaine [mycologist and ardent proponent of mushroom eating], of course, pronounces them delicious […], suggesting they be sliced and fried like a Wiener schnitzel.” Arora himself tries octopus stinkhorn eggs and reports that they left behind “a sticky spore mucilage […] which clung to our throats and tongues so tenaciously that we were still trying to wash it away several hours later” (p. 774). As recently as 2014, Alan Davidson in his Oxford Companion to Food states: “There seems to be no authoritative survey of the edibility of stinkhorns, nor any reason to suppose that many of them can be eaten by humans with pleasure and safety (except, perhaps in the ‘egg’ stage, before they have burst out and the evil-smelling slime has formed).”⁵

(Caution: if you’ve been heartened by Captain McIlvaine’s enthusiastic approval and are planning to taste those mushroom eggs in your back yard, make sure you are actually dealing with stinkhorn eggs, and not a poisonous look-alike like Amanita eggs. Also note: some stinkhorn species are said to be poisonous.)

Stinkhorns are too disgusting to eat […]. Nevertheless, people have tried eating the cooked eggs of some species after removing the slime layer. I reluctantly tried one bite of a cooked stinkhorn egg just once, so I could speak about the experience first-hand. I noticed very little flavor and a markedly unpleasant texture before I spit it out! […] I added [dried mature stinkhorn] to a soup, and found it to have no flavor, and a weird squishy texture that people in China apparently like, but I found very unpleasant.
“Wildman” Steve Brill, naturalist/author (blogpost)

In the West, therefore, stinkhorns are generally avoided. But in East Asia, the pendulum swings the other way: one stinkhorn species, the same Phallus indusiatus as in the picture above, has been collected for centuries as a choice edible reserved for special occasions and, since 1979 when it was first successfully cultivated in Southwest China, it has become more widely available, but no less treasured.⁶ Phallus indusiatus grows in tropical regions around the world, including parts of Central and South America and Africa. In Asia it is consumed not just in egg form, as North American field guides suggest, but also in mature form. In fact, it is in this latter, mature state that you are likely to find it at major or well-stocked Asian grocery stores and markets, in the dried fungus section. Phallus indusiatus is usually sold dried, without the smelly pileus or the tough volva, under the common name bamboo fungus or bamboo pith fungus (simplified Chinese: 竹荪; traditional Chinese: 竹蓀; pinyin: zhúsūn). The West’s basket stinkhorn is the East’s bamboo fungus. [Editor’s Note: At least three stinkhorns have been cultivated in China, including Phallus rubrivolvatus and Phallus fragrans. It is unclear to me whether bamboo fungus is a true Phallus indusiatus or a different Phallus species].

There are a few hundred kinds of edible fungi in the world, and bamboo fungus looks the most lovely, tastes the most delicious, has the most abundant nutrition and is the most valuable for medicine use. Therefore, it is also called “the botanical chicken.”
Anon., ChinaCulture.org

In the US as in East Asia, bamboo fungus is not the cheapest mushroom around, although its price has decreased significantly as cultivation techniques improved, from approximately $770/kg in 1982 to $10-20 in 2000 (Hong Kong prices, converted to US dollars).⁷ This might be one of the reasons that it is still a bit of a novelty in more Northern parts of China. In an informal survey of my Chinese acquaintances, some people didn’t recognize the mushroom at all or had only recently been introduced to it, while others said it was common, if a bit expensive. The divide seems to be along geographic lines. Whether they grew up with it or not though, every Chinese person that I interviewed pronounced it “delicious,” “fantastic,” or something along those lines. A far cry from the few American bloggers, who found it “unpleasant” or flavorless.⁸

In the name of science (and gastronomy), I procured a packet of dried bamboo fungus from an online Asian grocer. The mushrooms arrived intact, but they are very fragile, which is not surprising given the open, spongy structure of the stalk and the thin mesh-like skirt. This is in fact one of the reasons why bamboo fungus is not sold fresh: it is crisp and easy to break, thus difficult to transport. My packet of dried fungus had a rather persistent smell: earthy and mushroomy, but with a strong hint of musty hay and almonds. It lingered on my fingers after handling, but it was not unpleasant, it did not overwhelm my kitchen and it mellowed down significantly after soaking.

I rehydrated my mushrooms in cold water for a few hours. Different people rehydrate in different ways. Some recommend warm or hot water for faster rehydration, some believe cold water preserves more of the taste; some recipes advise you to soak overnight, while others state that a few minutes are enough. Either way, the rehydrated mushrooms are not rubbery and tough like rehydrated fleshy mushrooms (e.g. shiitakes); they are flexible, but strong enough that at least the stalk can be simmered in a soup for at least an hour without it breaking apart. Recipes vary in this regard as well; some will have you cook the mushroom for a few minutes, others will ask you to keep cooking it for an hour to extract more of the flavor.

So what about the taste? I side with my Chinese informants here; after simmering them in some homemade chicken stock for about 15 minutes, my stinkhorn stalks and skirts had a pleasant, mild sweetness. While they were not as “mushroomy-tasting” as their fleshier counterparts, they did pack a good punch of umami. But it is really for their texture that they are most prized in Chinese cuisine.⁹ The texture was indeed very interesting: smooth, silky, but at the same time subtly crunchy. This reminds some people of tripe or squid,¹⁰ but the bamboo fungus stalks are softer and more flexible than these, and the skirt is very delicate.

Bamboo fungus is traditionally used in rich chicken soups,¹¹ but you can also find it in hot pots, stir fries and stuffed. Google will find a few recipes in English, some of which I’ve collected below. Most English-language cookbooks do not mention it, but a Google Books search suggests that more recent cookbooks and some travel guides are more likely to contain a passing reference and a recipe or two.

Commercially-grown Phallus indusiatus is going strong in East Asia; there is a clear market for it and it is only likely to become more well-known and widely used. In the West, though, it seems unlikely that it will replace the harmless button mushroom in the hearts and stomachs of the American public. But in the meantime, if you’re an adventurous eater and a mushroom lover, this is one relatively easy to obtain mushroom that tastes much better than it looks. So don’t judge it by its cover.

This year Grandma couldn’t find impatiens (Impatiens walleriana) to plant in her flower beds. She’s always planted impatiens! But lately, impatiens have been sickened by downy mildew, caused by Plasmopara obducens. This plant disease has received attention the past few years because it decimates the most popular varieties of this annual garden plant. What you probably haven’t heard yet is the story of how impatiens, through sex, sheer luck, and the attention of one man, rose to the pinnacle of popularity only to be suddenly destroyed, all thanks to an unassuming downy mildew that has been lurking close to our back yards.

The story begins on shady river banks of east Africa, where cultivated impatiens have wild relatives. Compared to their domesticated descendants, wild impatiens are small, spindly, and have fewer flowers. They are unique in the way they disperse their seeds, using spring-loaded seed pods triggered by the slightest touch. Almost a century ago, impatiens were introduced as ornamentals to South and Central America, where their seed flinging habit allowed them to escape gardens and become naturalized.

It was these rogue impatiens, growing on a shaded Costa Rican roadside, that captured the attention of one Mr. Claude Hope. It’s an understatement to say Hope had a green thumb. A Texan by birth, he was a brilliant horticulturist who worked for the US government during World War II, researching plants in Central America. Much later he recalled in an interview that he’d first noticed cheerful impatiens on his walk to work during those years. Something about that plant, hardly more than a weed, inspired him. He recognized impatiens’ potential to become a popular garden plant. After the war, he put down roots in Costa Rica, developed a successful seed company, and began breeding impatiens, shaping them into the popular plants we know today.

Plant breeding is a discipline at the intersection of gardening and genetics. Every vegetable on a grocery shelf, and every packet of seeds is a product of this process. It’s a sexy science, beginning when two plants are intentionally crossed. Their best offspring are selected for favorable traits by breeders and interbred over multiple generations, which might take years or decades. Once ideal plants are produced, they are usually only crossbred with each other, or clonally propagated with cuttings. Maintained this way, plants keep producing offspring with the desired physical traits. The impatiens varieties Claude Hope bred had more and longer-lasting blooms, in a range of bright colors. They were shade-tolerant and perfectly suited for North America’s gardening appetite.

Most impatiens planted today owe their existence to the Father of impatiens’ six year-long breeding effort. For decades impatiens have been a garden staple, but recently this plant breeding success story took a dark twist. Hope considered himself extremely lucky for the relatively short time it took to create what became the most popular annual plant in America. But the same gardens, window boxes, and parks that he helped transform face a serious threat today. Mr. Hope died in 2000, and did not live long enough to witness their devastation by downy mildew.

Impatiens downy mildew is caused by Plasmopara obducens, which is not a fungus but an oomycete, a group better known as water molds. They resemble fungi to the naked eye, but their closest evolutionary relatives are diatoms and brown algae. Other oomycetes are also plant pathogens, and some cause sweeping epidemics and crop losses. One infamous example, Phytophthora infestans, caused Ireland’s Great Potato Famine in the 1840s and remains an important disease of potatoes and tomatoes today.

Impatiens downy mildew infects a range of impatiens varieties, but most of the time infections are not fatal. It’s just bad luck that it is truly devastating when it infects the most popular kinds of impatiens– hybrids developed by Mr. Hope from Impatiens walleriana. When these plants are infected they go from mild symptoms, with fuzzy white mildew on the undersides of leaves, to complete defoliation in the blink of an eye. Symptoms are less dramatic on other impatiens varieties– maybe only a little yellowing of leaves and stunted growth.

Here’s a time lapse of impatiens being killed by downy mildew.

Downy mildew sprouts on the underside of leaves as a fuzzy grey carpet, making millions of spores that are spread by rain and wind to other susceptible plants. When a spore lands, it can infect by growing directly into a leaf, or by producing swimming spores (zoospores). Zoospores swim across plant surfaces in thin layers of dew or rain, initiating multiple points of infection. A third kind of tough, thick-walled spore (the oospore) can endure in soil, perhaps for years, waiting for a susceptible plant to infect.

Unlike some pathogens that have been introduced and cause problems in a new environment, impatiens downy mildew is native to North America. It’s been documented here since the 19th century infecting pale jewelweeds and spotted touch-me-nots, native relatives of Impatiens walleriana. On these native hosts, symptoms are mild, sometimes little more than purple leaf spots. We have evidence of downy mildew infecting wild impatiens going back at least a hundred years. Impatiens have been popular for over thirty years, so why has this downy mildew become a problem in nurseries and gardens only in the past several years?

The factors behind the epidemic are under study by plant pathologists, while plant breeders search for disease-resistant varieties. We don’t know for sure, but we can guess that a random genetic change gave one lucky spore of our native downy mildew a new ability to kill Impatiens walleriana. The lucky descendents of this lucky spore found themselves surrounded by genetically similar, and thus similarly vulnerable Hope hybrids. This new downy mildew variant took off like wild fire. This is evolution in action. Luckily, not all impatiens varieties are vulnerable to downy mildew. For now Grandma can switch to New Guinea impatiens, or one of a handful of new, resistant impatiens varieties.

Aside: Recently I learned that the Library of Congress has added this blog to their historical collection of Science Blogs. I think that’s pretty cool. Thanks for coming along on the ride.

Fungi are lively things, but (like this blog) you can seldom spot them moving. That’s why we like time lapse videos here on the Cornell Mushroom Blog, to hurry things along a bit. Our fungus of the day barely needs speeding up — pleasingly, it’ll do its thing while I share a cup of tea with visitors at my lab table. Drop one in water and in ten minutes it unfolds, revealing a plump center that you can puff with a poke. As it dries, it slowly closes up, ready for teatime tomorrow. A small wonder.

There are two kinds of earthstars that look similar only because they’ve hit upon the same delightful solution for spore dispersal. This one, Astraeus, has the infinite ability to open and close, open and close. Species of Geastrum look like kin, but do their trick just once and remain open for business. Whereas Astraeus earthstars are the sisters of boletes, Geastrum earthstars are relatives of stinkhorns.

I found my Astraeus earthstars among the dunes of Cape Cod, Massachusetts. Then in my local Asian grocery, I found a bright red can from Thailand, marked “Astraeus hygrometricus,” and here you see a photo of its contents in my palm. Astraeus earthstars are a valuable wild mushroom in Thailand, and are picked before they even open up, then sold both fresh and canned. But I’ve never heard of anyone gathering earthstars for dinner here in North America, and it made me wonder.

Unlike you, perhaps, I didn’t wonder about what recipe to use for my Cape Cod earthstars (well past their prime; already open and full of powdery spores). No, I wondered what we mycologists often wonder — are those Thai earthstars really the same thing as these American ones? And, not surprisingly, I found that the answer is: No, they are not. So I don’t plan to cook up any American earthstars, because I don’t know whether they are edible. Just because they are in the same genus doesn’t mean they should be (think, Amanita phalloides (deadly) vs. Amanita caesaria (yummy)).

For the longest time, we thought all Astraeus earthstars were the same species, and we called them all Astraeus hygrometricus (the water-measurer; the barometer earthstar). But the littlest thing in biology, under scrutiny, often turns up surprises and intrigues. That’s what Phosri and friends found,² when a closer look revealed that there are many different lineages of earthstars, and they had to describe some new species to accommodate them all. So now we know that my Cape Cod earthstars are quite different from those you’d eat in Thailand, in both their habitat and their genetic make-up.

When something you thought you knew needs dividing into many pieces, there’s bound to be issues with names. Practically every Astraeus collected over the last two centuries has been called A. hygrometricus. Now we know most of them are not, which means that only some of the things we thought we knew about this species are actually true. The real Astraeus hygrometricus occurs in France and Turkey. My can of “A. hygrometricus” from Thailand is one of the two Thai species: A. asiaticus or A. odoratus. And what shall we call our American species?

American Astraeus earthstars, so far, seem to be either A. morganii (like mine– plumpish; spores not too bumpy) or A. smithii (littler; warty spores), and I’d bet there are other species too, awaiting discerning eyes. I can sense you groaning at this proliferation of names… but don’t. You don’t need to know the names of every little thing — you can just call them Astraeus if you like, or barometer earthstars. But WE need to have names for every little thing. Not having names for things makes them almost impossible to perceive. They’re genetically different, and they’re probably ecologically quite different in ways we’ve never noticed. Without good names it’s hard to answer important questions like “is it edible?” and “what’s it doing?”

What IS it doing, anyway? Sand seems an improbable place to find fungi. You’ll be pleased to hear that under the shifting sands my Cape Cod earthstars are hooked up to the roots of dune plants, forming friendly relationships (ectomycorrhizae!) that benefit both plant and fungus. Their starry fruits and clever dispersal mechanism help them spread spores that find new seedlings to team up with; new dunes to stabilize.

I promise we will get to fungi, but first, let’s talk about ladybugs. There’s a new ladybug in town, and it’s not as charming and adorable as our old favorites. It’s the Multicolored Asian Ladybug, Harmonia axyridis. They were introduced to North America in the 20th century to eat pesky aphids: one ladybug can eat 200 aphids a day. This is really their most charming characteristic— their other attributes make them undesirable invasive insects (Koch 2003). They appear to be displacing friendlier native species (check out the Lost Ladybug Project). They have also become household pests, since they overwinter in huge aggregations on or in our houses. If you have them in your home this winter you know that if you piss them off, they produce a foul stink known as “ladybug taint.” If you’re a winemaker, ladybug taint can ruin a whole batch of wine if you accidentally squash some ladybugs along with your grapes. Even in low numbers they give wine the taste of rancid peanuts or rotten peas (Mansell 2009). Worse, ladybug allergy (that’s right, ladybug allergy!) is increasingly a problem for humans whose houses are ladybug overwintering sites (Goetz 2009). No laughing matter, and to top it all off, they sometimes bite. They’re just not very nice ladybugs.

So, on to fungi. Today I present three: one friend of ladybugs; one foe; one just a nuisance. The nuisance is the coolest: Ladybugs don’t get fleas— but these labouls are the closest thing. They are blood-sipping parasites that form small colonies on the backs and bellies of ladybugs. With the naked eye they can be mistaken for plant pollen. Mordecai Cubitt Cooke, an early popularizer of fungi, dubbed them “Beetle Hangers” for their weird hook- or club-like appearance (Cooke 1892).

Beetle hangers belong to a diverse and surprisingly host-specific group of fungi, the Laboulbeniales. Of the 2000 described species an impressive 80% parasitize beetles, and many live only on a particular species of beetle. One of the first descriptions of this group was by Harvard’s Dr. Roland Thaxter. He did foundational work on the group, writing and illustrating a goliath five part series titled Contribution towards a monograph of the Laboulbeniaceae. Among the descriptions and illustrations that make up this work is Hesperomyces virescens, the green beetle hanger, which infects a variety of ladybugs.

A green beetle hanger’s entire life cycle takes place on a ladybug. The hard exoskeleton of insects seems unwelcoming, but beetle hangers are well suited for it. The life cycle begins with a spore that gets stuck to a ladybug. First the bottom cell of the spore, which will become the “foot,” grows until it penetrates the body of its host by creating a small gasket-like hole called an “o-ring” (Weir and Beakes 1996). Once inside, it grows a branched structure to absorb nutrients, like the roots of a tree. Its growth inside the ladybug is limited and causes little harm. Once the foot is firmly planted, the upper part of the spore grows to form male and female structures that allow it to reproduce. Ascospores made after fertilization are ejected by a trigger mechanism when touched— BANG! That’s how beetle hanger spores are spread among ladybugs, or to new parts of the same ladybug (Weir and Beakes 1996, Brodie 1978).

The green beetle hanger takes advantage of ladybugs’ gregarious and promiscuous behavior to get around. Female ladybugs can spread infection during matings with different males, and vice versa. Even encounters with infested deceased ladybugs can spread the fungus. Green beetle hangers spread easily among ladybugs overwintering in groups—infection can increase by as much as 40% (Nalepa and Weir 2007, Weir and Beakes 1996). Yet despite the probable discomfort and sometimes impairments to movement, most infected ladybugs lead full and happy lives (Weir and Beakes 1996, Brodie 1978).

While green beetle hangers may be irritating but harmless to ladybugs, another fungus of multicolored Asian ladybugs is actually beneficial. Multicolored Asian ladybugs are typically infected by parasitic fungi called microsporidia. Normally, microsporidia are disease organisms, but scientists were baffled to find them abundant in ladybug blood, causing no negative health impacts. On the contrary, it turns out they are a ladybug’s secret weapon: when native ladybugs eat microsporidia-infected eggs of multicolored Asian ladybugs they are essentially poisoned. The microsporidia may even be behind the antibacterial activity of their blood (Vilcinskas et. al 2013). By helping to eliminate native competitors these microsporidia contribute to their hosts’ success in taking over the world (Williams 2013, Vilcinskas et. al 2013).

Microsporidia are microscopic single-celled fungi. They are thought to have an ancient origin. Although microsporidia are widespread in animals and especially insects, with over 1200 known species, they are generally not good for health. For example, in immune compromised humans they cause a chronic disease called microsporidiosis. Incapable of reproducing outside of a host’s cells, they survive and are transmitted from cell to cell and animal to animal as egg-shaped spores. Once a spore makes contact with a host cell a long tube is ejected. It acts like a syringe to inject the microsporidium into its host. Once inside a host cell exploits its hosts cell machinery to make copies of itself, producing new spores that repeat the cycle.

Now we’ve met a nuisance fungus and a helpful bioweapon, but every story needs a villain. If you’re sick of ladybugs getting into your wine and your house, here’s a fungus to kill them. Beauveria is a genus of molds that kills bugs. Various strains of Beauveria have been developed as biological controls of pest insects. Maybe we can find a strain perfect for killing off ladybugs who’ve overstayed their welcome, as Roy and colleagues (2008) suggest. These fungi don’t have to be injected or “inhaled,” they have the ability to drill their way into a ladybug and eat its insides (luckily they don’t eat me or you). Then they burst gloriously forth and grow the deceased ladybug a fuzzy white jacket.

One ladybug: three different fungi, each adapted to live with its host in a different way. You can see why we think the world of insects will be a great place to discover a lot of fungal diversity.

An entertaining way to confirm a mushroom is a Russula is to throw it at something (a tree, the ground, a friend) and watch for its explosion into little pieces. This is satisfying because it confirms the brittle nature of the mushroom while at the same time reducing the risk that you will attempt to identify it, a process sure to end in tears. Michael Kuo (of mushroomexpert.com) feels that advanced Russula identification “is a joke” with species distinctions frequently based on subtle, arbitrary and highly variable differences.¹ It’s always good to be able to identify mushrooms to avoid eating toxic species, but with Russula, so far, this is quite a challenge. Luckily most Russula species aren’t harmful beyond a stomachache, however, one of a few toxic exceptions is the deadly Russula subnigricans.

Russula subnigricans is a mushroom first found in Japan in 1955. Since then, it has also been found in China, Taiwan and has sometimes been reported in the Southeastern US.* It is one of the blushing Russulas, but it’s not shy: once broken, its tissues slowly bruise red. Two images of this species are shown here.^6,4H They don’t look very similar to me— the cap colors and gills look very different (let’s go with the first one, which appeared in a book⁶ coauthored by the very mycologist who first described it). This demonstrates the variability of Russulas even within a species, or perhaps differences in opinion between experts due to the difficulty of identification. Scientists aren’t the only ones struggling with Russula identification; many people have misidentified this species and eaten it. One study reports that it caused a quarter of the 852 mushroom poisonings in the past 18 years in Southern China.⁴ Half the people who ate it died!

The horrible thing about R. subnigricans is that it causes rhabdomyolysis, or the breakdown of muscle tissue. This is a painful process that can lead to kidney failure. Rhabdomyolysis can also be induced by physical damage to muscle tissue, or abuse of drugs like cocaine. In R. subnigricans, the toxin that causes it is cycloprop-2-ene carboxylic acid— only recently discovered in 2009.³ Earlier studies found toxins dubbed russuphelins, but it was later questioned whether the researchers had identified their toxic mushroom correctly (darn you Russulas!).⁴ The reason it has taken so long to identify the real toxin is that it’s unstable, making its isolation and detection difficult; it is also not directly toxic to cells, further complicating experiments.³ Although the exact mechanism is not understood, the toxin appears to trigger a cascade of reactions in the body, resulting in widespread breakdown of muscle. If the muscles in your heart or your diaphragm get broken down, you’re in trouble as your heart may stop, or you may stop breathing. After muscle tissue is broken down, massive amounts of one of its chemical components (myoglobin) are carried to the kidneys. In high enough doses, this causes kidney failure. In terms of toxicity, 2.5 mg/kg of dried mushroom kills mice. If humans are like mice, then two or three mushrooms can kill a person.³

Symptoms usually begin 30 min to 2 hours after ingestion and include nausea, vomiting, diarrhea and abdominal pain. These are common, non-specific symptoms of mushroom poisoning. However, within 6-12 hours victims also have general muscle pain, speech impairment, convulsions, pupil contraction, stiff shoulders, backaches, trouble breathing and myoglobinuria, which turns their urine red and contributes to kidney failure. Most deaths occur 12 to 24 hours after ingestion.⁴

Treatment for rhabdomyolysis in the case of mushroom poisoning is mainly supportive— there is no specific antidote. The victim is kept hydrated and dialysis may be performed in an attempt to prevent kidney failure. The main factors dictating survival are how much mushroom was consumed and how soon after ingestion treatment begins.

A few other mushrooms are known to cause rhabdomyolysis, including Tricholoma equestre (the Man on Horseback). It is globally widespread and was a treasured “edible” mushroom— at least until scientists discovered it caused rhabdomyolysis. A 2001 study examined the 12 cases of delayed rhabdomyolysis in France from 1992-2001. This study documented victims experiencing symptoms of rhabdomyolysis 24-72 hours after the last meal of T. equestre. Of the 12 patients, 3 died. To confirm T. equestre was the culprit, the authors experimented with mushroom extract on mice and determined it was indeed the cause.⁵ The specific compound causing rhabdomyolysis was not determined, but this mushroom is no longer invited to dinner. Now it reminds us to be humble, as there are many things we don’t know about this species yet, and furthermore about over 90% of fungi.

These deadly mushrooms serve as a reminder to respect mushrooms and correctly identify them before eating them. Mushrooms can do some pretty crazy complicated stuff and make some weird molecules we don’t understand. Even familiar mushrooms like T. equestre that we thought were safe sometimes turn out not to be. Although we now know the toxic component of R. subnigricans, we are still only beginning to understand its effects. With this in mind, if you find a Russula, you might as well throw it at a tree and enjoy the show…

It’s hard to learn about fungi. And eww, why would you want to? Aren’t they all either diabolical molds or poisonous mushrooms? Of course not. Fungi are an amazingly old and diverse kingdom, yet hardly anyone knows much about them, even us mycologists. After all, we think that we’ve only even given names to about 5 to 10% of them. Not a typo.

So let’s say your interest is piqued— you want to know more. Good for you. You could go the mushroom route: join a club, attend forays, eat stuff, and learn from eclectic mushroom gurus. Yes, do that, it is fun, you will learn interesting things, and it will give you a window on some of the wonders of fungi. But most fungi –the vast majority of them– are not mushrooms. At some point you will start to wonder about all the rest.

Here is where most people get stuck. How do you begin to learn about the incredible variety of fungi? How they are related to one another; how they live? If you can even find one, you could take a college course: you’ll learn the secrets of fungi, capture them, and observe them up close and personal. Do that, excellent, but it’s not for everyone. You may hurt your brain or your wallet. If you are very brave, skip the class and get hold of a mycology textbook. You will fall asleep more quickly at night, because although the texts are good, they are dense, use lots of terminology, and are not so pleasingly illustrated. You might skip the textbooks and read some of the growing number of books that explore the stories of fungi, that is good too, yes! do that. Yet, if you are a visual learner, the emphasis on text over images may make you wish for more.

So do this: buy Jens Petersen’s book, The Kingdom of Fungi. Sadly, I haven’t met Dr. Petersen, but he is clearly very cool, and adventurously knowledgeable, and very adept with a camera. He’s created the missing piece, a joyful photo-essay on the glorious diversity of fungi. It will not hurt your brain or your wallet. Because of all the beautiful photos, you will hardly even notice you are learning things, that you are developing a structured view of the kingdom of fungi. As a teacher, I find that this structure gives us a comfortable place to put future learnings. That is, if you know a little about the kinds of fungi, you will have an easier time predicting the qualities of some fungus you’ve just encountered for the first time. His classification scheme is refreshingly modern; his pages are beautifully laid out. His photos of itty bitty fungi will (finally) convince you of the beauty and intricacy of smaller landscapes, and you may even find yourself wishing for a hand lens.

Fungi are cool, but they are foreign to us, and hard to get a grip on. So this question comes up a lot — how do I learn more about fungi? Here is a book for you and me. Not too much text, not much jargon. Enough order to help you build a scaffolding for your growing understanding. And lovely photographs to please anybody–over 800 of them in just 265 pages (have a look inside). There’s even an unknown fungus, the Amazonian mystery tongue, which is sticking its tongue out at us all, as fungi often do. I’m so happy to see this book, it makes for a great start in fungi.

Wishing you a happy journey and much joy in your fungal education.