by Greg Marley
THE FAIRY RING MUSHROOM
OR SCOTCH BONNET
(Marasmius oreades)
This is the best known among the many mushrooms that are capable of forming fairy rings (hence the common name) and is a regular sight in almost any grassy area that isn’t overly fertilized and manicured. Evidence of the rings is common throughout the growing season in the form of expanding bands or rings of stimulated green growth at the leading edge and retarded growth inside the ring or arc. Mushrooms fruit throughout the growing season, but most predictably in early summer and again in the early autumn in the Northeast and similar climates. I find it easiest to spot the lush green growth of the ring in late spring or mid- to late autumn.
DESCRIPTION
The common name Scotch bonnet comes from the typical shape of the mushroom’s cap. In the early stages, it is rounded and develops a distinctive broad central knob called an umbo on the cap as it opens fully. The caps and gills are generally the same color, off white to pale tan and darkening to tan with age or repeated “rehydration resurrections,” which refers to a mushroom’s ability to dry out and then return to a fully active moist state when wet weather returns. (See more on this below.) The surface of the cap is bald and smooth without any scales, hairs, or slipperiness. The gills are free to attached (but never decurrent), broad, and widely spaced. The spore print is creamy white.
ECOLOGY
The mycelium of the fairy ring mushroom can remain dormant for long periods of time as it awaits the proper moisture conditions for growth. Because it has evolved as a persistent perennial in a favored environment, you often can count on the Scotch bonnet to fruit yearly or several times yearly over many years.
One fascinating feature of this mushroom is its ability to produce fruiting bodies that are capable of completely drying out, only to rehydrate later and continue to grow and produce new spores. For a mushroom that grows and fruits on open grassland under the full onslaught of the Sun and faces the vagaries of intermittent rain showers, this represents a great reproductive advantage. For years, observers were aware of this rehydrating ability, but scientists were unsure whether spore production and cell division continued after the mushroom dried out; in other words, it was unclear whether the mushroom truly remained alive when rehydrated. More recent observations and studies have confirmed that this is indeed the case. The mushroom remains alive, though inactive, when it’s desiccated and returns to full active spore production when it rehydrates. Scientists have been working toward a better understanding of the mechanisms that allow living organisms to seemingly return to life following this “rehydration resurrection.”
Sea monkeys are perhaps the best-known example of rehydration resurrection. They arrive in the mail as a packet of powder that is actually a herd of encysted brine shrimp—tiny shrimp-like crustaceans native to salt ponds and salt flats all over the world—that, due to the feast-or-famine water cycle of their natural environment, have evolved adaptations that enable them to go into “suspended animation” or dormancy when their desert environment dries up. During the encysted state, there are no measurable signs of life and they can survive for long periods of time, enduring extreme temperatures both hot and cold. But sea monkeys quickly return to normal functioning when salt water is added to the powder.
Resurrection ferns and other such ferns exhibit similar patterns in feast-or-famine environments where there is not enough moisture. I remember the first time I collected the fronds of the Stanley’s cloak fern in the foothills of the Sandia Mountains outside of Albuquerque, New Mexico. These ferns grow in microclimates created by overhanging granite ledges or under the protection of huge granite boulders where any rain that falls flows off the rock into these protected oases. Growing at an altitude of 6,500 feet in an area that receives less than 10 inches of rain per year, the small fronds of these ferns curl up upon drying into tight ball-like clusters with powdery white, waxy undercoated surfaces facing out. In times of wet weather, the fronds unfold and photosynthesis begins anew.
Studies of organisms able to manage rehydration resurrection, including fairy ring mushrooms, show that as they dry out there is an increase in the production of certain sugars such as trehalose. As the dried organisms rehydrate and reactivate, they consume the trehalose. It seems that the increased levels of these sugars play a significant role in preserving the integrity of cell walls as the tissue dries.6 Studies confirm that the fairy ring mushroom has been shown to increase and decrease levels of trehalose as it dries out and rehydrates.
LOOK-ALIKES
There are a few mushrooms that grow in grassy areas and can resemble fairy ring mushrooms. A few brown-black spored members of the Panaeolus or Psilocybe genera prefer this habitat, so avoid any mushrooms without off-white gills. The poisonous sweating mushroom, Clitocybe dealbata, also grows in grass and easily can grow along with the fairy ring mushroom. It has a dirty-white cap and closely spaced white gills attached to a white stem or slightly decurrent. The sweating mushroom contains muscarine and will produce markedly unpleasant symptoms, including copious sweating, tearing, and salivating within thirty minutes in anyone who has eaten it.
CAVEATS
Because fairy ring mushrooms thrive in domesticated lawns, there are a couple of specific caveats regarding their collection for food. I have made the mistake of not collecting this mushroom several times, thinking I would return in a day or so to gather the bounty. There were two mistakes in that assumption; the first had to do with the unfortunate habit we suburbia dwellers refer to as mowing the lawn. Uncountable delectable mushrooms succumb to those rapacious whirling metal blades each season. The second mistake was perhaps more pernicious and had to do with other alert mushroom collectors (including many who have learned the art at one of my classes) getting the bounty ahead of me. The final caveat involves the reality that, like many other mushrooms, the fairy ring mushroom is able to absorb and retain some pesticides and heavy metals. This mushroom grows best in unpampered lawns anyway, so avoid collecting them from a well-manicured lawn where there is a good chance that chemical treatments have been in use.
EDIBILITY
Marasmius oreades is considered by many mushroom fanciers to be a good to choice edible. Though small in size, it is common to find many individual fruiting bodies in an arc or fairy ring, so a sizable quantity can be collected on a good day. The tough fibrous stem is best removed, as it doesn’t add much to the quality of the dish. I find that if I pinch the upper stem between my thumbnail and first finger, the cap will easily and cleanly pop off the stem. David Arora suggests bringing scissors along when collecting for clean stemless Scotch bonnets. Not surprisingly, given its ability for rehydration ressurection, M. oreades dries easily and drying is the preferred method of preservation. This is one mushroom I wouldn’t hesitate to collect in a semidry state. The fairy ring mushroom cap is the perfect size and shape to use whole in a number of dishes. Several years ago I used a jar full of dried caps in a Thanksgiving bread stuffing for our holiday turkey to great reviews. Cooked, this mushroom retains a chewy texture and has a mild distinct flavor, making it a welcome addition to many dishes.
Fairy rings present us with an opportunity to meditate on the wonder and the intricacy of the natural world. They also offer a phenomenal opportunity to teach children about nature and the life cycle, ecology, and mythology of these fascinating fungi. Fairy rings can be formed by a number of mushrooms, and in every instance they evoke a whiff of magic.
Of airy elves, by moonlight shadow seen,
The Silver token and the circled green.
ALEXANDER POPE, Rape of the Lock, 1712
16
FUNGAL BIOLUMINESCENCE
Mushroom Nightlights
Some things which are neither fire nor forms of fire
seem to produce light by nature.
ARISTOTLE
Walking along a forest path at night is a magical pastime and an exercise in awareness. As your vision shrinks, your awareness of the sounds, s
mells, and tactile impressions grows. Any cone of light emanating from a flashlight is quickly absorbed by the black hole of darkness. For people who aren’t at home in nature, a mature, dense forest can seem intimidating even in the daylight with its limited vista, enveloping intimacy, and dense canopy. But at night it is altogether more intense. The crowded crush of the trees seems like its own universe and the slightest sound of a twig snapping underfoot is both magnified and insignificant. Scary childhood fairytales—with their ravenous wolves, huge hairy spiders intent on our doom, and strange wizened characters offering fruit that appears too good to be true—actually seem plausible. There is a reason that ghost stories are told around a campfire deep in the forest. We are descended from forest-dwelling ancestors, and back when we hunted in the forest, other creatures in the forest also hunted us. It was not a particularly safe place. At night we feel more strongly connected to those roots. They seem to be only one coyote howl away.
Twenty-five years ago, when I was teaching environmental ecology in a great program offered by the Tanglewood 4-H Camp and Learning Center in Lincolnville, Maine, we would liberate kids from the confines of the classroom and bring them into the living laboratory of the forest to offer hands-on education about our connections to nature. For middle schoolers, we offered an overnight program where, in the late evening following dinner, we led small groups on hikes into the night-shrouded forest. Entering a mature white pine forest at night with a group of thirteen-year-olds is like escorting them into the Cathedral of St. John the Divine. Knowing adolescents, at first I expected giggles, gibes, and horseplay, but the majesty of the dark forest always elicited a quiet reverence in groups of normally restless kids. When we had them turn off their flashlights and sit in the dark forest, the reverence deepened into a profound, though nervous, respect for their insignificance. And if we knowingly planned our nocturnal respite in an area with a stump covered by honey mushroom mycelia or colonized by the fruit of the luminescent Panellus or jack o’lantern mushrooms, the reverence turned to wonder. It always took a minute for to the kids to adjust their eyes to darkness, but then someone observant would whisper, “Hey, what’s that weird light there?” If it was honey mushroom mycelia, they were referring to streaks or patches of greenish glowing light across the surface of dead wood on damp ground. If we were lucky enough to be next to a patch of fruiting jack o’lantern or Panellus, then a pale greenish light would emanate from the gills of a dense cluster of caps.
Bioluminescence, foxfire, fairy sparks, torch wood—whatever you call it, it is a wondrous and sometimes frightening sight to come upon unexpectedly along a dark path in the forest. The word bioluminescence literally means “living light.” Close to fifty different species of fungi worldwide have demonstrated luminescence, including the three common and widespread North American mushrooms mentioned above. The number of identified luminescent species continues to grow as we explore the fungal diversity of the tropics. Recently five new species of luminescent Mycena were discovered in Brazil.1 People always have been captivated by the phenomenon of living fungal tissue giving off light in the night. In some folk mythology, glowing wood was seen as a sign of fairy revelry, which is what gave bioluminescent fungi the name fairy sparks. And although I believed for years that the name foxfire came from the Appalachian mountains (it is, indeed, used in that region), the name originally comes from the French “faux fire” or false fire and is used to describe glowing fungal light.
There are many stories of people using luminous fungi, including accounts of soldiers in the Pacific Islands jungles in World War II who used clumps of glowing fungi for light when they wrote letters home.2 These same soldiers would lace a bit of glowing mushroom onto the barrel of their rifles during night patrol or guard duty, to signal friendly status. In Europe, there are accounts of the use of clumps of torchwood to mark pathways through the forest. Perhaps Hansel and Gretel did not use breadcrumbs to mark the path out of the forest from the witch’s house. If they used Foxfire in the night, they would still be as lost in the daylight as they were if the birds ate up their trailing crumbs.
Foxfire also has earned a footnote in the annals of marine history. The first submersible boat designed to attack another ship was built in 1775 by the colonial American patriot David Bushnell and was used during the Revolutionary War. Though unsuccessful in its attempt to attach an underwater mine to sink the British naval vessel HMS Eagle, the small submersible boat marked a milestone in naval warfare.3 In early trials, Bushnell realized that use of a candle for light in the enclosed boat would quickly deplete the oxygen and shorten the boat’s underwater time limits. He turned to another great inventor of the period, Benjamin Franklin, for ideas. Franklin suggested use of foxfire, which was used to give out enough light to view the compass and depth gauge.4
Although no amount of knowledge can take away from the magic of sitting next to a pale, glowing bit of wood in a dark forest on a quiet fall night, scientists have made great strides in their understanding of bioluminesence—a mystery found not only deep in the dark forest in fungi, but deep in the dark ocean among other organisms as well. A mile or more deep in the ocean, where no surface light penetrates and perpetual darkness is the norm, anglerfish and dragonfish have evolved the use of luminous organs and appendages to attract unwary prey and potential mates. At depths in excess of 5,000 feet, many deep-sea inhabitants depend on dead or dying organisms, mostly microscopic in size, to filter down from the fertile surface for their food. While the deep ocean floor offers as much shelter and habitat as shallower waters do, locating a mate and, for larger carnivores, finding prey is not so simple. Among the range of remarkable adaptations to this dark sea life is the evolution of specialized light-emitting organs in a number of species of vertebrate fish and a range of invertebrates like shrimp and marine worms. Many have patterns of light-emitting organs along their heads and the sides of their bodies. Others, specialized predators with plus-sized mouths and an array of teeth sure to give young children nightmares, have developed glowing appendages that hang off their snouts in front of their gaping jaws. These inviting beacons lure the unwary to dinner. The adaptive advantage in easier access to food or to reproductive success in a completely dark world can explain the energy devoted to develop and maintain such specialized, light-emitting organs.5
Far from the ocean bottom, a similar wonder takes place across dark summer fields in New England. Growing up in the Southwest, I never witnessed the marvel of fireflies winking across dark fields until I spent the summer of 1971 in upstate New York. North America has no species of luminescent beetles living west of Kansas. I call fireflies beetles because that is what they truly are: They are members of several families of predaceous beetles native to many parts of the world, but most common in tropical regions of Asia, Central, and South America. Though adult fireflies are not always luminescent, the larvae and the eggs are. In larvae, the presence of luminescence is thought to communicate to potential predators that their glowing target possesses certain chemical defenses making a meal of “glowflesh” an unpleasant experience. (I have found no explanation for the glowing eggs, but perhaps they too advertise their toxic nature.) The various patterns of light emitted by the adult males as they fly serves as a bright signal to potential mates and helps in differentiating both among species and among members of the same species. The females watch the male antics and signal who they like the most with single bursts of light, like flashing a dazzling smile across a crowded dance floor.
The chemical reaction that produces light in deep-sea creatures, fireflies, and luminescent fungi is essentially the same. It involves a reaction between a substance known generically as luciferin and a generic enzyme luciferase, which in the presence of energy-releasing ATP and oxygen breaks down, thereby releasing light. Unlike the more common light-emitting reactions in nature, such as fire, almost all of the energy used in the bioluminescent reaction is released as light with almost none wasted as heat and, as a result, is sometimes referred to as c
old light. In comparison, the incandescent light bulb wastes about 90 percent of its energy as heat.
There are few written records of bioluminescence from the time of Aristotle and Pliny the Elder until the mid 1600s, in part because of deep suspicion and superstition related to any strange or unexplainable phenomena. The Italians historically believed that the dancing lights of fireflies were the souls of their departed loved ones and dreaded their coming. In the late 1600s, a more thoughtful and scientific approach swept across Europe. The famous philosopher, early chemical genius, and relentless observer Robert Boyle determined that air was needed in order for luminescent fungi to glow. Using an enclosed jar, he determined that when the air was pumped out, creating a vacuum, the fungal glow stopped, and restarted only when air was reintroduced into the jar. At the time, it wasn’t known that air is composed of a mix of gases; later studies determined that the chemical reaction is dependent on the oxygen in the air. Two hundred years after Boyle’s experiments, Raphael Dubois, a French marine scientist working with luminescent clams and a species of beetle, determined that there were two components in the clams responsible for the light emission when mixed. He named these luciferin, a heat-stable chemical fuel, and luciferase, a heat-labile catalyst that, when added to the fuel, jumpstarts the reaction. Over time it was shown that each different light-emitting organism made its own unique combination of luciferin and luciferase. The reactions require the presence of oxygen that is converted into carbon dioxide.6