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About midway through my walk in New York City’s Green-Wood cemetery with Sigrid Jakob and Potter Palmer, I spot a golf ball-sized orange orb poking up through mown grass. “A yellow puffball! You found it,” Jakob says. It’s a hazy, humid July morning, but the past few days have provided a break from the summer rains. Before we passed under the gothic arches and into the cemetery’s expansive grounds, Jakob warned me that there might not be much to see with the recent dryness. “Today is not the day to look,” she says. 

Once we’re among the headstones, however, there’s something for us to pause and examine every few steps. ”There’s a number of fungi here that are normally very rare, like our yellow puffball,” she says. “We’ve seen them maybe once [elsewhere] in New York City, but here they’re in the hundreds.”  

The puffball anomaly is just one of many mysteries Jakob and Palmer, both self-taught mycologists, are hoping to shed light on. Together, they lead the Green-Wood Fungi Phenology Project, a crowdsourced effort that documents the surprising array of mushrooms present in the almost 200-year-old cemetery. So far, they say nearly 300 unique species have been identified within the gates—many rare, and some entirely new to the continent.

Jakob and Palmer fell into their work surveying Green-Wood’s fungi almost by accident, but through it they’ve highlighted what citizen science can do: bring a community of mushroom hunters together and discover a hidden biodiversity treasure trove. The group’s observations underscore the notable fungi diversity in the cemetery, along with the critical relationship between mushrooms and its beloved, old trees—partnerships of mutual survival.

The project also demonstrates how unique greenspaces like urban cemeteries can play an unexpected, yet important conservation role in cityscapes. Recent research from around the world has shown that the sacred spaces support a wide array of life, including many protected species that would otherwise be squeezed out by the human thrum. Though Jakob and Palmers’ study is in its early stages, both hope that cataloging the tinier residents of Green-Wood could be a stepping stone to broader discoveries. 

Mushroom hunters and amateur mycologists in Green-Wood Cemetery
Sigrid Jakob (left) and Potter Palmer (right) leading a public fungi walk in Green-Wood cemetery. Photo: Courtesy of Potter Palmer

There’s a common joke among naturalists that mycologists, who survey the ground, are always running into bird watchers, who eyeball the treetops. The first time Palmer heard the line, it was in reference to Jakob, who’s the current president of the New York Mycological Society—a nonprofit that leads mushroom walks throughout the city. She grew up noticing and admiring the fungi around her village in Germany, but assumed there weren’t many in her first few decades of living in New York City. One day, though, a switch flipped. “I started to see them,” she says. “Just suddenly they were everywhere.” She started identifying one and after another, and eventually, realized that there was a local club of enthusiasts where she could glean more knowledge.

Palmer, on the other hand, began simply as an amateur naturalist who discovered fungi through his strolls in the cemetery. “There are so many of us who haunt Green-Wood,” he says. Initially, he got involved in a project tracking seasonal changes through tree monitoring, but then slowly began noticing the array of interesting mushrooms at his feet. He used the iNaturalist app to record his findings, and that’s how he and Jakob connected. “I started to get my pictures ID-ed by Sigrid,” he says.

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To make those identifications, Jakob uses a backpack-sized laboratory that contains all the equipment needed to extract and amplify fungal DNA, including a microscope and a Polymerase Chain Reaction (PCR) machine. Once she’s processed a sample, she sends it off for sequencing to reveal each fungi’s genetic code. But that’s only for the trickiest circumstances. “I definitely exhaust every other avenue,” she says, “including spore prints, microscopy, field guides, and just looking at, smelling, and tasting the thing.” 

Searching for answers intuitively is part of what makes the hobby fun, she adds. “Otherwise you’re paying four bucks for somebody to give you a name, but you don’t really understand the mushroom any better.”

One of Jakob’s most surprising identifications so far has been Inocybe porcorum, a diminutive brown, gilled mushroom that had previously only been found in a single location in Finland. She verified the ID via DNA sequencing, but the finding brings up more questions than answers. “The two continents have been apart for like 500 million years. So to find two species that have not even speciated away from each other, on two continents is like, ‘how did that happen?’,” Jakob says. It’s possible that the fungus was transported here, but it was found growing connected to the roots of a native tree, meaning it didn’t likely travel to Brooklyn with a European seedling. 

Another similar shock was Psathyrella madida, a nondescript species Jakob says had only ever been found before in a boggy Swedish meadow She also identified a West Coast bolete she believes hitchhiked into Green-Wood in the roots of a planted Douglas fir.

Jakob concedes that some of these mushrooms could be more widespread, but are just overlooked, particularly in the US where fungi are less well-surveyed than in Europe. However, some species (like those yellow puffballs) get more attention. Lots of mycologists have searched for them, and seen them only occasionally, she says, indicating true rarity.

And rare species aren’t the only thing the surveys have uncovered. Palmer notes he’s also observed some unexpected relationships between more familiar fungi and trees. “Sometimes you see domestic species that are supposed to only grow with eastern white pines that have actually started to collaborate with Himalayan pines,” he says.

”And some trees have a fantastic array of mushrooms around them, while some trees have absolutely none,” adds Jakob, even in the same species. “We don’t know what’s going on, but we’re interested in finding out.”

Orange puffball mushroom with spores
Jakob pulls apart a yellow puffball, revealing the collection of spores inside. Photo: Lauren Leffer

Here’s what we do know. Fungi generally fit into one of three ecological roles: decomposers, parasites, and symbiotes. The first break down organic matter, recycling nutrients back into the ecosystem. In a city, decomposers could be found on anything from dead leaves and grass clippings to piles of poop on the sidewalk.

The second, parasitic fungi, siphon off resources from plants and other organisms rather than scavenging scraps. Sometimes they can spread and kill swathes of full-grown trees, like the oak wilt first found in Brooklyn in 2016.

But the fungal lifestyle Jakob and Palmer refer back to most frequently during our walk are the symbiotes, or mycorrhizal mushrooms. These species have quid-pro-quo relationships with specific plants. Through interlocked plant root and fungal filament networks, the hosts offer sugars produced from photosynthesis to the fungi, which provide minerals and other necessities in return. Many mycorrhizae are more efficient at uptaking, transporting, and unlocking minerals from the soil than their plant hosts—facilitating growth that would otherwise be impossible. The group contains most of the prized edibles like truffles and chanterelles, which only thrive around mature, healthy trees. 

Green-Wood is an accredited arboretum. There are 690 unique species of tree growing there and about 7,000 individuals, many of which are more than a century old.Without the symbiotes, Jakob imagines that many of the cemetery’s trees would become sick or die of nutrient deficiencies. “Apparently up to 50 percent of a tree’s sugar gets funneled towards their mycorrhizal partners for minerals,” she says. And trees are getting a whole boatload back from the fungi, including about half of their needed water, according to the work of forest ecologist Suzanne Simard.

The trees of Green-Wood play a big role in why there are so many different types of fungus—but they aren’t the whole story. “The cemetery has a lot of microenvironments that are conducive to many different types of fungi,” says Palmer. “It’s pretty diverse in terms of terrain and different vegetation in different places.”

What’s more, “there’s no trampling, so it’s relatively undisturbed” Jakob says, contrasting the cemetery to nearby Prospect Park where she describes lawn picnics, sports games, and pets as potential limiting factors on mushroom diversity.  An emerging body of research worldwide supports Jakob’s idea that the ways urban cemeteries are used and maintained helps them foster biodiversity in otherwise wildlife-poor places.

Even in densely populated cities, cemeteries remain comparatively tranquil islands, pruned and filled with greenery to offer peace.

“Cemeteries are sacred places, where most of the drastic landscape changes (cutting trees, ploughing grasslands, etc.) [have] not happened in the past. Especially in the case of long-established ones, nature is quite undisturbed,” Löki Viktor, a plant ecologist at the Centre for Ecological Research in Hungary, writes in an email.

In a 2019 review on the topic, Viktor and his colleagues looked at nearly 100 published studies and found 140 protected species listed among the existing biodiversity surveys of cemeteries. They concluded that urban cemeteries offer refuge for rare and endangered species and are important to consider in conservation efforts.

While fungus-specific studies are limited, in 2020, researchers found that urban and rural cemeteries in the Czech Republic provide habitat for lichen. Lichens spread and propagate in a similar manner to fungus (and are actually a symbiosis between fungi and algae), relying on distribution of spore-like cells, and can be sensitive to environmental factors like air quality, says lead researcher Jakub Horák.

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Further, in a 2019 paper, urban ecologist Harini Nagendra found “impressive biodiversity,” including unusual and rare species, among the trees in cemeteries and other sacred spaces, in Bangalore, India. She had previously surveyed parks across the same area and says that, anecdotally, the trees in cemeteries “look much larger.” So, why is there so much life hiding among the dead? Planting trees in cemeteries can be part of deeply ingrained traditions and beliefs. In Hindu cemeteries, for instance, Nagendra says, “if you have a loved one then you plant a tree at their grave, and you plant a specific species.” And cemeteries are often simply less trafficked than other green areas of cities, she adds, echoing Jakob and Viktor.

Even in densely populated cities like Bangalore or New York, cemeteries remain comparatively tranquil islands, pruned and filled with greenery to offer peace.

An urban cemetery is a surprising sanctuary for fantastic fungi
Jakob risks a taste of Amanita, a fungi group with hundreds of species worldwide. Photo: Lauren Leffer

Back in Green-Wood, every time I pose a question, Jakob and Palmer seem to have more of their own. ”Do healthy trees attract more fungi? Do more fungi mean the tree ends up being healthier?,” asks Jakob. These questions don’t yet have clear scientific answers, which has left the opening for citizen scientists to try to tackle them, she adds.

To do that, they’ll continue working with their team of a dozen or so hyper-involved participants they’ve recruited through iNaturalist. “We’re kind of in an intensive survey phase,” Palmer says. But in the next year, he hopes to start cross-checking their fungal maps with existing survey results on the cemetery’s dirt and trees. “Green-Wood actually has quite an extensive database of the soil quality of the canopy. And I know that they’re open to allowing us to start to use that data.”

Definitive answers or not, Jakob will certainly continue scanning the Green-Wood grounds. Even a decade of wandering the same cemetery hasn’t taken away from the magic of finding mushrooms. “Fungi are weird,” she says. “They’re like the freaks or the emo kids who sit by the side of the class who nobody talks to.” But that’s what she loves about them: rejected and misunderstood, fungi are still everywhere. It’s a fitting analogy for a group of people hanging out in a cemetery.

Mid-conversation, I watch Jakob take the tiniest shred of a mushroom cap between two fingertips and place it in her mouth. “This is an Amanita, which are some of the most toxic fungi known to mankind,” she says. I pause, concerned, but she quickly clarifies: “This one doesn’t have a ring [on the stem], so we know it’s actually one of the edible ones.” Nonetheless, she spits out the pulp to the side, having gotten the information she needed from the fungi’s funk, and we continue on.

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