Every winter and spring when conditions are just right, something magical begins to happen in California, Oregon, and Washington. After a few good rains, some cool nights, and a bit of sun, webs of white mycelium in countless beds of wood chips begin to produce mushrooms.
Strolling around any San Francisco neighborhood it’s not uncommon to see a dozen species of urban mushrooms growing in gardens and the landscaped areas of office buildings or apartment complexes. But for those in the know, three are of particular interest: the potently psychedelic Psilocybe cyanescens, Psilocybe allenii, and Psilocybe ovoideocystidiata.
P. cyanescens and P. allenii are two of the hundreds of psilocybe mushroom species that contain the hallucinogenic compound psilocybin. Research on these psychedelic fungi is still in its infancy, but most current work is focused on exploring their potential to treat mental health issues such as post-traumatic stress disorder and depression. There is still much to learn about their biology, ecology, and evolutionary history.
For starters, where they grow in the wild is actually a bit of a mystery. “You can walk around the woods forever in California and you will not see them,” says Alan Rockefeller, chief mycologist at the international pharmaceutical company Mimosa Therapeutics. And yet they are by far the most commonly foraged psychedelic species in the U.S., in part because the Pacific Northwest has become the epicenter of these wood-loving magic mushrooms popping up in urban landscapes.
These mushrooms “feed on wood that's had a lot of the good stuff already taken out of it” explains Jason Slot, a biologist who studies fungal evolutionary genetics at Ohio State University. They don’t want the freshly fallen wood, but stuff that is a bit more broken down, he says. “The sugars are long gone, and other fungi have already had their chance at the simpler carbohydrates like cellulose.” Put simply, they love wood chips.
So like rats, pigeons, and cockroaches, these most potent of psychedelics not only survive but thrive in urban and suburban environments that are filled with mulch beds.
“Humans do extremely unnatural things—erecting large concrete jungles where we lay down copious amounts of wood chips,” says Jordan Jacobs, a fungi forager and chemist who runs a lab in Oregon that tests magic mushrooms. “It's fascinating that a psychoactive mushroom that has potential long-lasting effects on human consciousness has decided that this ecological niche suits it well.”
Exposed habitat and a psychedelic defense
P. cyanescens and P. allenii are both small—never growing more than two or three inches tall—and have chestnut brown caps, white stems, and dark purple spores. The only difference between the two is that the caps of P. cyanescens develop a characteristic wavy edge, which is why they’re commonly called wavy caps. P.ovoideocystidiata, also called ovoids, look similar but are a little bigger with thicker stems. Like most psilocybe species, these mushrooms turn a deep purplish blue when they are crushed or bruised.
Around the world, magic mushrooms are commonly found in herbivore dung, where the animal and other fungi have already taken a pass at the nutrients. Slot thinks it is this preference for exposed habitats, like wood chips and manure piles, that may have led to the evolution of psychedelic compounds.
“Fungi are really nutritious to eat,” says Slot, and because neither dung nor loose pieces of wood offer much protection, he believes mushrooms likely evolved the ability to produce psychoactive compounds as a defense against grazing animals. Research has shown that psilocybin binds to certain receptors in the brains of rats, so Slot hypothesizes that “high populations of small mammals could provide enough selection pressure on the mushroom to support the evolution of a neuroactive compound.”
Researchers have yet to seriously investigate whether animals experience any psychedelic reactions from eating psilocybin, but considering how humans respond to them, Slot points out with a chuckle that “it’s not necessarily a given that all animals don't like to get high.”
The geographic origins of these magic mushrooms are similarly mysterious. P. cyanescens was first described in a 1946 paper written by Elsie Wakefield, a mycologist and plant pathologist who found them in the Kew Gardens in Great Britain. Kew is a sprawling botanical garden with a collection of tens of thousands of living plant and fungal species collected from all over the world, in addition to millions of dried samples.
“That is certainly not where it evolved,” says Rockefeller, who is one of the most well-known mycologists studying psilocybe species. He can rattle off Latin names faster than most people can understand them and has a near-encyclopedic knowledge of mushrooms on the West Coast of the U.S.
He says that genetic evidence points to either Australia or the Pacific Northwest as their ancestral home. But today, P. cyanescens is a global species whose natural history is fundamentally entwined with people. They have been documented in most of the U.S., throughout Europe, in South Africa, and in New Zealand and Australia.
The origin story of P. allenii is similarly shrouded. But in the 2012 paper that first described P. allenii, Rockefeller and his colleagues call it a synanthrope, an organism that thrives in places built by and for humans. Though P. ovoideocystidiata’s origin is less mysterious—it grows wild in the Ohio River Valley – today all three fungal species are in lockstep with human expansion.
“They exist because of the environments that we make. Wherever they came from, who knows if we’ll ever know,” Slot says. “The cyanescens are just following where we mulch.”
Wood chips, moisture, mushrooms
In relatively cold and wet areas like Washington and Oregon, P. cyanescens and ovoids can be found growing in more natural environments, including coastal dune grasses and along creeks, but what they really love is regularly watered wood chips. And once you move farther south into California, all three species become exclusively urban fungi.
Rockefeller has spent more time than most searching for magic mushrooms, and he brings the unique perspective of a naturalist to his foraging.
“They really like it if the wood chips are irrigated,” he says. “I definitely see them in the wood chip beds of Golden Gate Park. Office parks are also a really good habitat.” Apartment complexes in the Bay Area are much the same. And in a wonderful twist, according to Rockefeller, “you will see them at the police station and city hall.”
Jacobs, the recreational mushroom forager who runs a testing lab, found his first magic mushrooms on the Humboldt State University campus where he was an undergraduate. “I was coming out of an exam on a Friday, walking home to my apartment, and on the way found Psilocybe allenii. And well, that's cheaper and better than beer.”
According to Rockefeller, urban magic mushrooms aren’t exactly rare, but they aren’t going to be sprouting from every bit of mulch.
“If you only have a few square feet of wood chips, you have way less than a one-percent [chance] of finding them there. But if you can find some sort of office park with a square mile of wood chips, then you can just walk around all afternoon and there will be several patches.”
How they spread
P. cyanescens, P. allenii, and P.ovoideocystidiata likely originated in the Pacific Northwest and Midwest, respectively. But they now grow across most of the U.S., in Europe, and in a few other shockingly distant parts of the globe. This begs an obvious question: How are they getting around?
The most straightforward answer is the natural one, explains Jessie Uehling, a fungal biologist at Oregon State University: The spores get carried by wind.
“Spores are like the seeds of a mushroom,” she says. “Air comes in and physically swirls underneath the cap, collects spores, and then goes on its way.” Those spores then land on an uncolonized patch of wood chips and, if conditions are right, begin to grow. “They’re poised to colonize a resource as soon as it becomes available.”
There is another theory in the mushroom community—part legend, part science—about how P. cyanescens manages to appear in so many places. In 2001 two British mycologists published a study looking at how wood chip-loving mushrooms, including P. cyanescens, were spreading around England. In it, they write that these species may have infested the wood chip supply chain.
Essentially, the thinking is this: Mycelium, the webby, root-like structure that decomposes material and from which individual mushrooms fruit, is living and spreading in the large piles at wood chip production or distribution centers. Anytime those wood chips are shipped somewhere new, the mushrooms tag along.
There is only anecdotal evidence of this happening in the U.S., and without a comprehensive genetic study, it is impossible to make any strong claims one way or the other. But as Uehling puts it, “anytime wood chips become available, you're going to see wood-decay fungi, including psilocybe.”
Jacobs says he has no doubt that magic mushrooms are in the wood chip supply chain. He’s heard stories about P. cyanescens growing alongside a road near a mulch factory where freshly chipped wood would fall off trucks. He also says he knows people who have bought plants from big box stores and nurseries only to have a psilocybe pop up.
While the wood chip supply chain question remains unanswered, every expert interviewed for this story agreed on one way magic mushrooms surely spread: humans. Rockefeller and Jacobs are themselves fungal Johnny Appleseeds.
“When I find them, I'll pull off the stem base and plant it in some fresh wood chips nearby,” Rockefeller says. It only takes a small piece of the stem and mycelium to start an entirely new patch. “These mushrooms are really effective at turning wood chips into dirt, so I'll come back a year or two later and the original spot won’t have any mushrooms. But all the ones that I planted in the areas nearby, they'll be fruiting.”
Every winter, the reported range of these mushrooms expands, to the delight of mushroom foragers. As legalization movements gain steam and the evidence grows ever stronger for magic mushrooms as powerful mental health interventions, it will be interesting to see where foraging in mulch beds fits into the evolving cultural and medical landscape.
“People are realizing how cool mushroom hunting is,” Rockefeller says, “and the driver for that is certainly psychedelic.”