On my very first guided mushroom hike at Joaquin Miller Park, 30 long years ago, I was gobsmacked at the idea of an immigrant mushroom! Spotting a pretty orange-red mushroom by the trailside, I asked its name. “A brick top, Naematoloma aurantiacum,” I was told, “and no one knows where it came from!” Beauty and mystery? I was hooked.
As the years passed, and my obsession with fungi deepened, I discovered that there have been lots of fungal introductions. But these mushrooms are so well integrated into our local landscapes that it is not always easy to tell who is a native and who is not. One clue is habitat: most introduced saprophytic species—fungi that feed on rotting wood and plant matter—aren’t found in intact forests. Instead, they prefer habitats that people have disturbed, like trailsides and gardens, compost heaps and wood chip beds. Especially wood chip beds. And therein lies a story.
Wood chips are the perfect fungal snack food: bite-size chunks of wood, with lots of surface area to glom onto, and no tough bark to get through. And this snack bar never ends: we humans keep adding more chips, year after year. But wood chips weren’t commonly used in the Bay Area before 1989. That’s when California’s Integrated Solid Waste Management Act went into effect. The act mandated that at least half our solid waste must be composted or chipped. Now when trees are removed, rather than getting carted to a landfill, or left to slowly rot, they are chipped in place and used locally.
The fungal dinner bell has been rung!
The first fungi to colonize fresh beds are not very visually exciting, according to James Downer, a retired UC Riverside professor and plant pathologist who is a wood chip expert. There are species like Phaenerochaete and Ceraciomyces, both low-profile, rarely noticed crust fungi, and Trichoderma, which produces a greenish mold similar to Penicillium. As these early colonizers enzymatically break down the lignin and cellulose in wood (the tough stuff that makes wood sturdy), they create heat. And as they respire, they produce water. By doing so they create warm, moist environments, ripening these beds for the next generation of fungal colonists.
Once the second round of fungi have eaten most of the wood, they make mushrooms as their exit strategy—spreading to new locations via spores. This is when all of that fungal activity becomes visible to our eyes. And the second round of fungi are much showier than the first.
Case in point: the brick top—the original immigrant mushroom that captured my imagination—which, by the way, is now called the chip cherry (and Leratiomyces ceres). It is to my eyes the most striking of our wood chip fungi, with its shiny cap in a crimson that fades to shades of orange, with contrasting dark gills. I traced its Bay Area history by consulting two editions of David Arora’s seminal field guide, “Mushrooms Demystified” (which we myco-enthusiasts refer to as MDM). In 1979, Arora called it “rare,” noted it had only been documented locally in San Francisco, and made no mention of it popping up in wood chips. By 1986, in the second edition of MDM, it was “common,” found from Santa Cruz to Santa Rosa. And wood chip beds were listed as its preferred habitat. Wood chip beds have fomented an alien fungal invasion!
Many of these mulch-loving newcomers fruit prolifically after rain and are visually striking. Some are choice edibles. Others produce compelling forms combined with repugnant odors. And some can make you hallucinate! Our local wood chip beds contain a fascinating diversity of immigrant fungi. Here are a few portraits of a few of the most interesting ones.
Chip cherry or red spy: what’s in a name?
The brick top/chip cherry/Leratiomyces ceres, fungus of many names, has now spread around the world. In Europe they are called redlead roundheads, and in Australia and nearby New Zealand, they are called Larrys. Aussies have the best slang!
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I prefer to call it the red spy—a name that it has garnered by the company it keeps. It often grows with hallucinogenic Psilocybe species in wood chip beds. With that strikingly bright cap, it is much easier to spot than those unobtrusive little brown mushrooms. Seekers of magic mushrooms can easily spot red spies on a drive-by, and then screech to a halt and check those wood chip beds for the mind-altering fungi they really want.
This close association was brought home to me one December, when I gave a mushroom talk to a large garden club in Berkeley for its annual Christmas dinner. I had encouraged attendees to bring in any mushrooms from their own gardens for identification after my talk. In the dark of that large hall, I spotted a woman approaching me, and saw that she had Leratiomyces ceres in a box, identifiable from across the room! But the lighting was so poor, I couldn’t confidently identify the little brown mushroom alongside it, even in hand. I should have known! The next morning, after examining that mushroom in the light of day, I alerted her to the fact that she also had Psilocybe allenii in her garden. As a dog owner, she was concerned about accidental poisonings, and hastened to remove them from her garden. Fair enough, but somewhere, psychonauts wept.
When a mushroom is this well-traveled, tracing its origin is extra difficult. But maybe the mystery has been solved? Some of my Australian colleagues, and various other sources, now believe Leratiomyces ceres is native to Australia, because it can be found in bushlands in eastern Australia: it also commonly occurs there in gardens and wood chip beds. It is for certain a world-traveling opportunist, on the lookout for new growth opportunities, whether at home or in far-flung places!
Magic is all around up
Speaking of magic mushrooms—they are closer than you think. Psilocybe species have been in the news recently as therapeutic entheogens, but they have been spreading their magic throughout the Bay Area for many decades, thanks in part to all those wood chips we keep dumping onto the land!
I was thrilled to spot my first Psilocybe cyanescens—aka cyan, or wavy cap—in a grassy median strip in San Francisco in 1998; magic mushrooms have a long and storied human history, including my own teenage years, back in the ‘60s. P. cyanescens is a rather nondescript small brown mushroom, but it’s easily recognized at maturity by those in the know, with its wavy cap, moist skin that can be peeled off like a piece of cellophane, and purple-black spores and gills. When bruised it stains blue, indicating the presence of psilocybin. It is a potent hallucinogen.
The Bay Area has no native species of Psilocybe. Yet they now grow here, in good years, by the tens of thousands (although individual patches are more likely to contain hundreds). Their greatest densities can be found in San Francisco and the East Bay, but populations also stretch up into Marin County and north to Santa Rosa, across to the Mt. Diablo foothills, and down into Santa Cruz. Their small, brown, bluing forms can fill gardens, grassy fields—and, yes, wood chip beds. Because they are small and unmemorable, they’re easy to miss, even when they are carpeting the ground.
Cyans were first noted in England at Kew Gardens in 1910, and formally published there as a new species in 1946. Their arrival here in the Bay Area is a bit murkier.
Psilocybe expert Paul Stamets suggests that they have been around since the ‘60s or ‘70s, although the Summer of Love was more about LSD than magic mushrooms. David Arora, in MDM, notes Psilocybe had been spotted in small numbers in San Francisco before 1979, and had perhaps been introduced “adventitiously.” These days, many people are deliberately introducing them into new areas. According to Stamets, our local wood-loving Psilocybe species are easily transplanted into new wood chip beds via cut-off stem-butts. No need for sterile cultivation techniques for these hardy little fellows!
In January of 2006, a potentially new and spreading species of Psilocybe found in San Francisco was provisionally named Psilocybe cyanofriscosa (“cyan” for its bluing, “frisco” for its locale), by the shroomery.com member Quankus. This new potent species was similar to the wavy cap, but its cap never became wavy at maturity, and it had other subtle differences. Local members of the so-called Blue Stainers Tribe rejoiced at this new addition to the local Psilocybe population!
In 2012, after presumably definitive DNA evidence was obtained, a trio of mycologists, including two from the Bay Area, Alan Rockefeller and Peter Werner, formally introduced this species to the scientific world—though sadly not as “cyanofriscosa.” It was instead named Psilocybe allenii, after John W. Allen, a longtime psilocybe enthusiast who pushed the authors to determine whether it was indeed a new species. Like its cousin the cyan, P. allenii grows in woody debris and mulch.
But the plot thickens. A recent paper from Australia provides convincing evidence that both of these local Psilocybe species may be mere synonyms of the shape-shifting Australian Psilocybe subaeruginosa. There has been some unsurprising pushback on this origin story from North American Psilocybe specialists with some skin in the game. No one likes their named species to be put on the back burner.
When the morels come to us
In contrast, the blushing morel is a mushroom that comes to us! Rather than being tied to a particular tree, in a particular forest, at a particular time, these morels can pop up anywhere, at any time in our urban/suburban environment. Behaving as saprophytes, they eat just about anything, including our abundant Bay Area wood chips. But they don’t just grow in wood chips. They can pop up in flower pots, on dirt-floored garages, and in fields of ice plant (Carpobrotus edulis) on the coast. I have even seen them growing out of the mortar between bricks. Now that’s adaptability! Their one downside is that they are not nearly as flavorful as natural and burn morels.
First described from Mexico by mycologist Gaston Guzman, M. rufobrunnea was long thought to hail from western North America. But a recent scientific paper from Turkey strongly suggests that they arose in the Mediterranean—and hints at how they might have arrived here in California. The blushing morel is associated with olive trees (Olea europea) in its native Cyprus, where it behaves as a mycorrhizal species. Some mushrooms are able to switch feeding modes, and this morel is clearly one. It is possible that M. rufobrunnea was first brought to California on the roots of olive trees. Since they can also be found growing in olive orchards in the Central Valley, they may still behave as a mycorrhizal species in California, in some situations.
How do fungi jump continents? And how do they survive once they get here?
One challenge to answering either of these questions is how much of the physical mass of fungi goes unseen, because it’s underground or hidden in wood. We rarely see the workings of the fungal body itself, mycelium—a root-like structure composed of fine, threadlike hyphal filaments that branch and connect and intertwine. Mushrooms, their aboveground fruiting bodies, are our charismatic entry point to the fungal world. But for the fungus itself, mushrooms are merely ephemeral spore factories, producing billions of spores in hopes of finding fertile ground, somewhere.
Because most spores colonize locally, they are unlikely to be how fungi spread from continent to continent. The mycelium, on the other hand, spreads for miles through soil, colonizes dead wood, and lurks within the heartwood of living trees. Some tiny fungi live harmlessly within the tissues of leaves (an “endophytic” lifestyle), while others in soil entwine their mycelia with the roots of trees and other plants, forming a partnership called mycorrhizae; where one goes, so goes the other.
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With hidden fungal presence everywhere, it is no wonder that fungi make their way to new places, when we move plants and trees, mulches, sod, and wood chips around the world. Even other animals can move fungi—dung fungi tag along in the guts of livestock. Birds carry fungal spores on their feathers. Fungi are the ultimate hitchhikers!
Once they get here, these immigrants have to make their way in a new land that’s already chock full of native fungal species. How do they do it? We are not sure. We do know that many different species of fungi share resources—native or not—and competition occurs everywhere. Some introduced species may have particularly aggressive mycelia, getting in first and dominating the food resource. We see this with the death cap (Amanita phalloides), which has spread throughout California since its first introduction to Monterey around 1938. Harvard post-doc Ben Wolfe, in a study at Tomales Bay State Park, determined that phalloides dominated the roots of coast live oak trees. Anecdotal evidence has shown that in some cases, death caps can temporarily push out other species like chanterelles. No one wants to trade a choice edible for the deadliest mushroom on the planet! But that’s an unusual case—most introductions don’t seem to be causing obvious harm. Another fighter: the warty knight (Melanoleuca verrucipes) is a recently introduced species that bears curiously sharp microscopic structures (cystidia) on its rhizomorphs (root-like structures at the base of the mushroom). Bay Area mycologist Else Vellinga has written that these little spikes may prevent predation by nematodes (tiny soil-dwelling roundworms), and give the fungus a competitive advantage.
But most importantly, by focusing upon disturbed habitat, all these immigrant saprophytes are able to gain a foothold in a place where natives are not already entrenched. Not only have we brought them in, but by altering the landscape, we have provided them with the perfect opportunity to thrive!
Our natural world is in constant flux, and these Bay Area immigrant fungi are here to stay. I for one welcome this ever-growing fungal diversity. Humans brought them in, and like any other immigrant—plant, animal or human—they merely want to survive. These world-traveling saprophytes seem to have found their niche within our disturbed spaces. They don’t seem to wholly displace native fungal species. And they are especially fond of wood chips, a widespread modern garden mulch that we gardeners are awfully fond of, too. They provide colorful accents in our mostly flowerless fall and winter months, bring ephemeral magic to our urban and rural landscapes, and sometimes even provide gourmet fare! Look for their colorful and intriguing forms when our fall and winter rains bring them to a wood chip bed near you!
GALLERY
More Fungal Immigrants to the Bay Area
Look for these introduced species in Bay Area wood chip beds and elsewhere, as noted. Some are new. Some have been around a while.
Mulch maid (Leratiomyces percevalii). A slender, tan-capped, dark-spored relative of the chip cherry first described from England in 1879. It has been in the Bay Area for many decades, and is now abundant in wood chips.
Latticed stinkhorn (Clathrus ruber). A Mediterranean species that looks like an orange wiffle ball. Arrived before 1950. Smells like death and poop, spores spread by carrion flies.
Warty knight (Melanoleuca verrucipes). First arrived in the Bay Area in 2004 with mulch. Has distinctive black-polka-dotted stem, and evil looking cystidia (microscopic poky bits) underground, which perhaps ward off predators. I found my first example in a sealed bag of mulch!
Orange pore fungus (Favolaschia claudopus) Adorable little orange ping-pong paddles on wood. First seen here in 2020, introduced from Australasia, slowly spreading. Although easily spread (introduced to Australia, New Zealand, Spain, and Hawaii decades ago), there is still no evidence that it displaces native species in those countries.
Descolea tenuipes. A curious small, bright-brown secotioid species (gills distorted, cap never opens) associated with eucalyptus. First Bay Area record from U.C. Berkeley, 1907. Rare.
Death cap (Amanita phalloides). Introduced from Europe to Monterey around 1938, on cork oak; in the Bay Area, has jumped hosts to coast live oak and pine and is now widespread. Contains deadly amatoxins, regularly causes poisonings in both dogs and people.
