My first step to becoming a naturalist was seeing a mushroom called Exsudoporus frostii, or Apple Bolete (pictured above). I was walking in the Middlesex Fells in Massachusetts and something blood red caught my eye. I thought it was trash. It turned out to be a deep red mushroom with a funky-looking webbed stem, as if it was covered in vibrant cobwebs. Under the cap bubbles of yellow liquid contrasted with the red pore surface. It was striking, a little gross, and absolutely gorgeous. Thus began my obsession with fungi, and ten years and many mushroom-themed gifts later, I now have the privilege of sharing the beauty and brilliance of fungi with others.
Below are profiles of some charismatic mushrooms that you can find in the Northeast through the seasons.
Note: don’t consume any mushrooms that you didn’t buy at the grocery store or farmers market, unless you’re a professional forager or a mycologist!
SUMMER
Boletinellus merulioides (Ash-Tree Bolete)
Last month, I wrote about ants that protect aphids in return for the sweet “honeydew” they excrete. It turns out that everyone wants in on the aphid action, including a funky local bolete (fleshy mushroom with pores). My parents learned that they had an ash tree they’d never noticed when we found Ash-tree Boletes in the yard. They’re mycorrhizal fungi—fungi that associate with the roots of certain plants. The relationship is usually a partnership; plants provide fungi with sugars in exchange for water and nutrients obtained by mycelial networks that extend beyond the reach of the plant’s roots.
Ash-tree Boletes are the children that had to do things differently. They partner with leaf curl ash aphids to get their sugars. These tiny green insects cause leaves to curl around them, providing both food and shelter. Females drop to the ground in summer and begin a new life in the soil, sucking nutritious sap from the roots of their host tree. The hyphae (thread-like fungal cells) of Boletinellus merulioides form hardened hollow balls called sclerotia around the insects while they’re tapped into roots and then absorb the nutrient-rich honeydew they excrete. The insects feast in their mycelial shelter while the fungi gets the sugars it needs for growth.
If we were to personify the ash trees, we might wonder if they feel betrayed. Thankfully, as a native insect with natural predators, leaf curl ash aphids don’t generally threaten healthy ash trees. Emerald ash borers, introduced insects, do kill healthy trees, and don’t need any help from aphids. As these invasive beetles decimate ash populations in North America, we’re seeing Ash-tree Boletes less and less. The fungi has been designated Threatened by the IUCN Red List. If you do find a healthy ash, check the fifty feet around it for brown mushrooms with off-center stalks, dimples around the edge of their caps, and large yellow pores that are arranged radially, giving the pored surface a veiny look.
FALL
Pleurotus ostreatus (Oyster Mushroom)
My dirty little secret is that I don’t actually like the flavor of this culinary favorite, but I’m absolutely fascinated with how it lives and consumes nutrients, particularly with its strategy for acquiring nitrogen. Nitrogen makes up 78% of our atmosphere, yet very little of it is in a form that living organisms can consume. This presents a challenge; nitrogen is required to build amino acids, nucleic acids, proteins, and many other biomolecules. We can credit bacteria with converting atmospheric nitrogen into bioavailable forms like ammonium and nitrate, but it’s still hard to come by. Organisms therefore have to hustle for the nutrient, and sometimes, they have to kill.
Oyster Mushrooms are categorized as saprophytic fungi, meaning they consume dead or dying organic material, like wood. Where there is organic material, there are nematodes, microscopic roundworms that live everywhere. Every four out of five animals on Earth is a nematode! Oyster Mushrooms have evolved special club-shaped structures on their hyphae that produce potent toxins which paralyze nematodes in about a minute and cause rapid cell death. The hyphae then move into the worm’s mouth and absorb their nutritious, nitrogen-rich insides. Disturbing? Kinda! Fascinating? I think so! The mushrooms you buy at the supermarket are the result of the most dramatic thing to ever happen to a bunch of tiny worms. Oyster Mushrooms subsequently provide nitrogen to other organisms when they’re eaten or decompose.
WINTER
Fomitopsis betulina (Birch Polypore)
You’ve likely seen this abundant mushroom that grows primarily on Paper and Yellow Birch. These tough brown mushrooms look like a hoof growing out of the tree trunk. The undersides are bright white and fleshy-feeling when fresh and rough, and yellowed when dry. They’re visible year-round because they tend to dry out rather than rot. They do, however, cause brown rot on their host trees, and continue to grow on them once they’re dead, making them both parasitic and saprophytic. Despite this fungi’s relationship to its host, it is far from a universal pest. Birch Polypores have been used as medicine for thousands of years. The properties of biological compounds found in this species makes it seem like a wonder-drug: antibacterial, antiviral, fungicidal, antioxidant, anti-inflammatory—there’s even promising research into anticancer properties of Fomitopsis betulina extracts. As if that wasn’t useful enough, it can also function as tinder (although you’d be even better off with Fomes fomentarius, Tinder Polyplore). A 5,000-year-old natural mummy found in the Alps in 1991, who scientists named Ötzi, was carrying pieces of Birch Polypore. They’re thought to have been used for medicinal purposes, although that’s not conclusive.
My favorite use for Birch Polypores, although I hope to never need it, is as a natural dressing for wounds. That fleshy underside can be peeled off in strips, and makes a flexible antiseptic bandage. Now, if you’re from the Copper Age, like Ötzi, this is a great option. If you’re a modern human with access to Band-Aids, you should stick with those. I implore you to never introduce any fungi to your bloodstream unless you are 100% confident that you know what it is. Even in theory, however, an abundantly available, biodegradable mushroom bandage is a pretty wicked concept.
If you find a Birch Polypore on a fallen tree, you can tell if it grew when the tree was still standing because the “hoof” will be facing sideways. If the hoof is facing down, it grew after the tree fell. Mushrooms like this grow with their pore surface facing the ground to protect them from injury and rain.
SPRING
Cerioporus squamosus (Dryad’s Saddle)
If you want to get rid of a stump, you could pay a guy $200 to grind it for you, or you could do it the old fashioned way: with patience and fungi. Dryad’s Saddle is saprophytic, and eats all the components of dead wood, including the polymer which gives wood its strength and stiffness, lignin. Lignin is very difficult to break down; only a few animals can do it, including termites, longhorn beetles, and water buffalo. Some fungi, of course, are born for the job. Cerioporus squamosus and other species that can break down wood in its entirety cause “white rot.” This superpower is accomplished with enzymes that digest wood into easily absorbed nutrients like sugars. These enzymes release free radicals, highly reactive molecules which are known for wreaking havoc on human cells in large quantities, and do the same to lignin’s irregular, tightly-bonded structures. Some fungi aren’t as good with lignin, and they cause brown rot, named because the intact lignin is brown. If it weren’t for these decomposers, you would have no yard, only stumps! What you’d lack in recreation space, you’d at least make up for in chipmunk-watching opportunities.
Dryad’s Saddle is a spring polypore. A polypore is a tough, shelf-like fungi with a spore-bearing surface of pores. This species is often one of the first mushrooms to pop up in early May. It grows on dead wood and from an off-center stalk, reaching a diameter of up two feet. It has handsome, feathery brown scales that give it another common name, Pheasant’s Back. Pheasant’s Back mushrooms smell like—I kid you not—watermelon rind. They’re a pleasant-smelling confirmation that spring has finally arrived, and that we’re getting enough rain! Check your local stumps between late April and early June for these powerful fungi.
Eager for more? We’ve got several mushroom programs this fall!
GILSLAND FARM, FALMOUTH
September 6: Intro to Mushroom Identification
Learn how to use field marks, substrate, and habitat to identify mushrooms with Field Naturalist Stacia Brezinski.
October 4: Mushroom Walk
Louis Giller of North Spore Mushrooms will lead this beginner/intermediate class on mushrooms. Wild foraging, cultivation, connections to wildlife, and the responsible harvesting of edible species will be discussed. Our class will culminate with a mushroom walk around Gilsland Farm.
FIELDS POND, HOLDEN
September 20: Fall Foraging Walk
David Spahr, author of Edible and Medicinal Mushrooms of New England and Eastern Canada, will lead a walk to show us what wild plants, mushrooms, and other natural treasures can be foraged for food, medicinal use and other purposes.
September 27: Mushroom Walk
Join author David Spahr as he takes you on a journey through the world of fungi. Time will be spent both indoors and outdoors learning about mushroom identification, folklore, collecting, and cooking.
