Mycophilia Read online

  There are other indicators of animal and fungi similarity, like the fact that we share 80 to 85 percent of the same ribosomomal RNA (where proteins are manufactured inside the cell). This is why it is so hard for animals to fight off fungal infections—what kills the fungus can also be harmful to humans. Indeed, it’s hard to believe that fungi are genetically closer to us than they are to plants because they seem more plantlike, but to put it in perspective, we are more closely related to plants than we are to the Escherichia coli (E. coli) bacteria that live in our guts.

  Most of the mycologists at the NEMF foray were kept busy identifying the mushrooms brought in by us, the paying guests. Indeed, within hours of arriving, people were trolling the landscaped edges of the parking lot, looking for mushrooms. In the rain. By 5:00 p.m. the signup sheets for the classes and seminars and forays were posted, and there was quite a bit of competition for spots, made even more frantic by the fact that there were about 25 people to every pencil. I didn’t know what to sign up for: Beech Forest? Great Island? Punkhorn Parklands? Someone pinned up a picture of a baby boletus mushroom and a couple of elderly ladies swooned over it, carrying on about the mushroom’s cuteness in high-pitched voices, like it was a grandchild. I signed up for the Beech Forest walk.

  The next morning at breakfast, the president of NEMF warned me that if I drank coffee before the foray my “back will get wet,” which I didn’t quite understand until someone on the bus explained that there was rain in the forecast and no outhouses in the forest. Our guide was Keith from Truro who looked like a fit Colonel Sanders. He said we might find Clitocybe nuda, the blewit, which grows under beech trees, and lots of colored lichens (lichens are included in mycological studies because even though they are a combination of a fungus and a single-celled alga or bacterium, the fungus part is really dominant, having enslaved its partner to photo-synthesize food for it). “I’m lichen that!” yelled Keith, who laughed uproariously then held his nose, acknowledging his stinky pun.

  In the park parking lot, Keith had us coordinate our watches, warned us about ticks, and pointed to the woods. We hiked in, at first as a group, but soon individuals peeled off like prospectors in search of their own claims. Beeches are beautiful trees. Even under bouts of rain, the beech forest emitted a pale green light, like the light from a firefly, and each of us staked out our particular grove to explore. I looked under my trees, kicking aside the wet leaf litter, finding nothing, and kept glancing at the groves taken by other hunters that I was sure were more fruitful. But then I remembered what David Campbell said about just standing still. And of course, that’s what it took to see them: a dozen lavender mushrooms scattered beneath the glowing trees, gently rebuking my covetousness.

  After lunch I sat in on the mycologist Renee Lebeuf’s “Mushrooms and Smells” lecture, where she explained that some people are anosmiacs—people who cannot perceive odors (commonly caused by brain jostling in car accidents)—and others are hyperosmiacs, people with an abnormally increased sense of smell,* and that one’s smelling ability can be developed. Renee, a low-voiced Canadian who clearly hated her microphone, pointed out that quick-rotting mushrooms rarely have smells, and that mushrooms smell less intense in cold weather. Some mushrooms have two smells, one for the stem and one for the cap, and dehydration can either increase or eliminate the odor of mushrooms. Then she covered the range of mushroom smells, sort of like a wine wheel: bitter (onion or garlic), bitter almonds, sweet almonds, anise, maple syrup, chicken bouillon, curry, rotten cabbage, bleach, mealy (like flour), cucumber, a smell like when you iron clothes, flowers of various sorts, bubblegum, tar, ether, honey, coconut, tangerine, raw potatoes, celery, pear, fish, rotting meat, burnt sugar, and sperm.

  Tom Volk’s tatoos depict fungal hyphae and spell “mykos.”

  One of the most popular presenters on the foray circuit is Tom Volk, a mycology professor at the University of Wisconsin-La Crosse. Lots of people in the mushroom scene call Volk the rock star of mycology, and for two reasons: He is adept at speaking to popular audiences, and he is heavily tattooed, with earplugs (not the kind that muffle sound) and blue bangs. Volk had the 8:00 p.m. slot on Saturday: the prime time of the foray. His lecture—part lecture, part stand-up act—called “Spores Illustrated” helped me understand some of the biology despite myself.

  When a mushroom is up in the woods, or anywhere else for that matter, it is up in order to disperse its spores, and most fungi use wind to do the job. A significant difference between spores and seeds is that spores don’t have a lot of food stored in them. As a result, spores are incredibly light, so light that mycologists surmise airborne fungal spores from Africa and Europe ride winds across the Atlantic and over the Pacific from China. But there are lots of different fungi, and some have evolved very strange yet effective methods of spore dispersal to ensure their survival.

  Spores are tiny. They are individually microscopic, ranging in length from 3 thousandths to 25 thousandths of a millimeter (the naked eye can’t see anything smaller than about 1/10 of a millimeter). They come in nearly every color imaginable, from white to black, and in a variety of shapes, and this probably has some bearing on how spores are dispersed. For example, some spores that are forcibly ejected are aerodynamic, like footballs; the asexual spores of some water-dwelling fungi are shaped like tripods that land on submerged leaves and grip them like little burrs. Looking at spores through a microscope is one of the ways mycologists identify mushrooms. (Another is checking the spore colors, and that is done by making spore prints—laying a mushroom cap gill side down on paper for a few hours—and observing the patterned dusting of colored spores.)

  Some spores hitch a ride on the aerial parts of plants. Some fungi eject spores in synchronized ejections that creates a mini air stream that increases the spores’ travel distance by 30 times. Others shoot their spores from catapult-like devices, the most impressive being the tiny Pilobolus, a mold that grows on herbivore dung. The 1-centimeter-tall fruiting structure (it’s not exactly a mushroom) grows above the excrement, orients its stalk toward the light, and shoots the spore glob on its tip 35 feet per second, summoning a thrust 10,000 times the acceleration experienced by space shuttle astronauts at takeoff. It shoots spores 6 feet up and 8 feet out, to land in a patch of grass where the spore is consumed by an herbivore, passes through its stomach where the animal’s internal heat activates the fungus’s spores, and then germinates on its dung, bringing the cycle full circle. (One hundred years ago, scientists used to have contests to see whose Pilobolus culture could shoot the farthest.) Another fungus, the sphere thrower, suddenly turns itself inside out in order to expel its spores.

  Fungi use animals to disperse their spore, too. Truffles emit the odor of certain mammalian pheromones that stimulates animals to dig up the fungus. (It’s an odor that turns on the human diner, too.) The netted stinkhorn, a truly repulsive-looking mushroom, smells like rotting meat (actually, it’s the spores that stink). It attracts flies, which pick up the sticky spores on their legs and transport them to another stinkhorn or a new habitat.* A rust fungus infects certain plants and induces them to grow dense leaves that look like flower petals at the tips of their stems. These pseudoflowers are brightly colored and smell sweet, and on them are sticky spores, which insects encounter and transport to other plants.

  Netted stinkhorn

  Bioluminescent mushrooms may glow in the dark to attract spore-dispersing insects at night-mushroom expert Larry Evans likes to call them insect discos. In the United States, bioluminescence, which is the result of a complex series of chemical reactions, is most commonly seen in the mycelium of the wide-ranging honey mushroom. Since mycelium doesn’t produce spores, it may be glowing to attract the predators of the microorganisms that predate the fungus. (Foxfire, also known as will-o’-the-wisp or fairy fire, is the greenish glow produced by bioluminescent mycelium. It was used to illuminate instruments in the first battle submarine. There are anecdotes about troops in both World Wars fastening bioluminescent fu
ngi on their helmets so they could spot each other in the dark without alerting the enemy.)

  The bird’s nest fungus, a cup-shaped fungus that contains a little clutch of spores that look like eggs in a nest, utilizes the energy of raindrops: When rain hits the cup, it splashes out the spores. The outer skin of puffballs, which hold all their spores inside, disintegrates or splits or is broken by mechanical forces like rain, hail, and small children, allowing the spores to blow out. Other mushrooms simply inundate the atmosphere with spores: The fairy ring mushroom releases millions of spores every minute.

  Spores can’t navigate themselves to a food source where they can safely germinate: They just have to be lucky enough to land in the right place, with some lying dormant for as long as 20 years, waiting, despite dehydration or extreme cold, for the right conditions. In order to increase their odds of success, mushrooms have evolved to produce lots and lots of spores. There are an estimated 1,000 to 10,000 fungal spores floating around in every cubic meter of air in the atmosphere, everywhere at any given time (which we constantly inhale but aren’t usually affected by because our immune system keeps them from causing trouble), so many that they may influence the weather cycle by acting as nuclei for water droplets and ice crystals in clouds, fog, and rain.

  The microbiologist Elio Schaechter wrote in his book In the Company of Mushrooms that a medium-size mushroom, one with a cap 3 to 4 inches across, can produce 100 million spores per hour. One wood decay fungus produces spores at the rate of 350,000 per second, 6 months a year. That’s 5.4 trillion spores a year for as many as 10 years. Tom Volk, who loves a cheesy analogy, said that a single basketball-size giant puff-ball contains 14 trillion spores, and if all 14 trillion spores germinated and matured they would circle the Earth almost 85,000 times. In 2009, I attended a lecture by the mycologist Bob Mackler, whose delivery was weirdly mesmerizing: Mr. Rogers on spore. “I dreamt of what would happen if all the spores germinated at once,” he said. “The mass of mushrooms they would produce would knock our planet out of orbit. It’s lucky that it is rare a spore turns into a mushroom.”*

  Tom Volk was on the bus with me the next day to visit the White Cedar Swamp trail in Wellfleet. When I told him I was from New York, he said, “I heart New York,” which took me a few minutes to digest because I knew he’d had a heart transplant in 2006. (In the beginning of his lecture he’d shown a slide of himself holding his heart. It looked like a glandy piece of veal in a Baggie.) When I gave him what I guess was a forced smile, he said the proper response to a pun was a groan.

  The swamp trail is right next to Marconi Beach, and while on it I could hear the relentless ocean. There were a variety of habitats, but I kept returning to the rolling dunes sprinkled with pine trees twisted by the coastal weather like miniature fossilized tornados. Speckled over the surface of the dunes were earthstars, a strange little fungus that is composed of a center puffball with ray-shaped arms that open like the rays of a star or the petals of a flower, inverting enough to lift the puffball a few centimeters aboveground so the spores have better access to wind. I gathered a few of these for an artist friend who is inspired by such things (they aren’t edible), following what seemed like a path of them over a dune, a brown milky way in a white sand sky. Each of those earthstars was puffing out little brown clouds of spore, and each spore was hoping to land on a bit of real estate that would meet its requirements for germination. When it does, the spore swells up and then spits out a hypha, a cell surrounded by a tubular wall. The hypha uses up the scant food reserves stored in the spore to give it energy to probe for an outside source of nutrition. If the hypha finds some food—and this is why it is so important that the spore land in a food-rich environment—it grows one cell at a time from its tip, becoming a one-cell-thick string of cells that is nine times thinner than a strand of hair (depending on the fungus). In most hyphae (the plural of hypha), permeable cross walls divide the cells, allowing some of the cellular contents to flow between cells, but generally retaining each cell’s genetic material. This string of cells is the fungus.

  Plants photosynthesize their food, animals ingest their food, and fungi absorb their food. A fungus secretes enzymes to the outside through its cell walls, including the tip of its hypha, that predigest whatever organic matter the fungus is specialized to consume. It breaks down the organic matter into its component molecular parts, like water, sugars, amino acids, and so on, and then absorbs the molecules, which gives the fungus the nutrients it needs to grow. “Fungi are so tiny they can’t eat their own food, so they basically have inverted stomachs,” said the mycologist Amy Tuininga. “Imagine you are lying on a giant steak. Your stomach enzymes seep out to predigest the steak, and then you absorb the steak through your skin.” Fungi actually live in their food supply, and as that supply becomes depleted, the fungus grows into the next food-rich environment, if one is available. And because fungi aren’t dependant on light to grow, they can live in dark habitats, like underground or inside wood.

  A fairy ring illustrates the spherical nature of fungus mycelium.

  The hypha grows one cell at a time—but it doesn’t grow in just one straight line: That wouldn’t be a very efficient survival technique. Rather, the hypha branches, growing in three dimensions if that’s where the food is and there is nothing in its way. Mycelium typically grows in a circular pattern to maximize its chance of finding nourishment. Starting from its food point of origin, the hyphae grow out in all directions, creating a ring of growing hyphal tips, sort of like the ripple wave created when you toss a pebble into a pond. This growth pattern causes the red ring you see when you have ringworm, the fungal skin disease. It is also the mechanism behind fairy rings, those mushrooms that grow in a ring on your lawn: The mushrooms indicate where the hyphae have grown.

  These branching hyphae become increasingly meshed and matted, creating a spiderwebby substance collectively called mycelium. When you break up a rotting log and you see that cotton-candy-like stuff running throughout the wood, what you are seeing is the mycelium: thousands upon thousands of hyphal threads, each one a single cell thick, and each probing tip secreting enzymes that break down the food source, each one a food absorption point. As one purply mycologist described it, the mycelium is composed of “transparent tubes, branching and rebranching [and in each] a rushing torrent of the living contents, the protoplasm, pressing toward the ever expanding tip.”

  Mycologists have measured intense pressure inside those hyphal tips. Turgidity (the pressure inside the cell, usually from water) is essential for growth in the face of obstacles. The mycologist Nicholas Money has measured fungal turgidity at 1 to 10 atmospheres (for comparison, the air pressure in a car tire is 3 atmospheres).

  Depending on the species, mycelia can grow into complex mats or ropey forms, and their size and density may be dictated by the available growing space and food supply—there can be as much as a ton of mycelium per vegetated acre. There is also some evidence that hyphae follow rules of predetermined growth like plants. There is a proscribed amount of space between the hyphal tip and the place where it branches, for example; but unlike the branches and twigs of a tree that grow smaller as the organism as a whole grows larger (there’s actually a name for that—apical dominance), hyphae are thought to grow the same all over the organism.

  Slime mold on the move

  You’d think that each individual hypha is after its own food, but actually, when one hypha comes in contact with a new food supply, the mycelium—the collective hyphae—turns its attention toward that new source and mobilizes its energy to grow toward it and exploit the new food. All the hyphae in a mycelial colony have the same set of chromosomes: They’re not individuals in a genetic sense, but clones, like a grove of aspen trees. Some mycologists describe fungal mycelium as a single-minded organism, and plenty of mushroom enthusiasts talk about fungal intelligence. The evidence most often cited is a Japanese study that tested the intelligence of slime mold by placing pieces of the mold in the middle of a 5-inch-squ
are maze with a food source—a bit of grain—at the exit points. Since the hyphae of fungi grow in every direction at once in search of food, the question was whether the mold would overwhelm the maze as a strategy or show intent in pursuing the food source by solving the maze. Researchers were surprised when the mold actually stretched itself out into a thin line and negotiated the maze to find the food. (Slime molds have since been taken out of the Kingdom Fungi and are distributed among several other classifications.)

  Given the proper and consistent conditions, there is no reason why a fungus couldn’t live indefinitely, growing and storing energy as long as there was a food source and space to grow into. And indeed, a fungus was discovered that turned out to be the largest and one of the oldest living organisms on Earth, and it’s still growing.

  Large fungal bodies, the largest (D) being the Humongous Fungus.

  In 1998, forest service scientists discovered a giant wood-decaying fungus, the Armillaria gallica that produces the edible honey mushroom, living in the Malheur National Forest in the Blue Mountains of eastern Oregon. The fungus spans 2,200 acres—the equivalent of 1,666 football fields—and is at least 2,400 years old. The fungus is largely composed of a type of mycelium called rhizomorphs (from the Greek, rhizo = root and morph = form), ropey bundles of hyphal strands with a protective melanized rind (melanin is the same stuff that protects you from UV rays by causing you to tan) that seek out new food sources, sometimes at great distances, even crossing over food-poor areas in order to find richer feeding grounds. In this way, the mycelium can and may live on and on, absorbing nutrients and growing ever larger. Because of the enormous size of what the newspapers dubbed “the humongous fungus,” it’s a bit hard to think of it as an individual, but it is. The Blue Mountain specimen has a single genotype. All its parts have the same set of chromosomes.