the rare trees hiding in plain sight in central park
i guess you could call this post an example of pumpkin picking
it takes a lot to get me to new york’s central park. while i recognize that it’s beautiful and probably the best forested nyc park for birdwatching, it’s also far from my house and a little too crowded for my taste. that being said, when i learned from the central park conservancy’s lisa kozlowski that it also hosts a population of the rare pumpkin ash tree, i decided that i needed to take a dedicated visit.
all of new york state’s native ash trees are endangered, most of them critically endangered, because of an invasive beetle called the emerald ash borer. ashes are still around—you can find green ashes on sidewalks across the city, for example. but the pumpkin ash is designated with the s1 rank by new york state, mainly reserved for plants with less than five statewide populations or other factors that make it especially vulnerable. this means it’s one of the rarest, most threatened plants in new york—and it lives in one of the world’s most-visited tourist attractions.
the plight of our ashes officially started back in 2002, when officials in michigan and southern canada confirmed the presence of a jewel-green beetle called the emerald ash borer infesting and killing ash trees. this introduced species from asia lays its eggs in the furrows of ash bark and the larvae dig into the wood to feed—ultimately preventing the tree from cycling nutrients and killing it in a few years. outward signs of an infestation include a yellowing appearance from bark falling off and D-shaped holes where the larvae exit the wood. ash trees overall are still common today, but the ferocity of the emerald ash borer infestation threatens many of them with extinction if we don’t act to protect them.
losing our ashes is a scary thought. they’re an abundant woodland tree whose seeds feed birds and which support around 300 species of native arthropod (including 100 species of butterflies and moths), many of which would not have a food source anymore should the ashes disappear.
the pumpkin ash was rare in new york even before emerald ash borers showed up. it has strict habitat needs, inhabiting swamp forests and wet areas. it’s mainly a southeastern tree, spottily distributed across the mississippi and ohio river floodplains, the coastal plains of the atlantic and gulf of mexico, and in parts of the appalachians. but new york sits at the northeastern tip of its range, so it’s especially rare here.
how rare? well, new york botanical garden co-founder nathaniel britton first documented the tree’s presence in the city in the bronx in 1904, but it was dropped from the list of new york city’s plants in 1934. it wasn’t until 2008 when it was rediscovered growing in the wild in nybg’s native forest, where you can still find some labeled ones standing along the bronx river. thanks to citizen science apps like inaturalist, new yorkers have reported pumpkin ashes in a few spots in the bronx, queens, and staten island—and in manhattan’s central park. you can read more about naturalist janet wooten’s discovery of a central park population of pumpkin ashes here, and these are the trees i’m taking you to see.
these ashes are hidden in plain sight in central park’s north woods area, specifically in the ravine. this recently-restored and well-maintained area surrounds a waterway called montayne’s rivulet, central park’s only natural waterway. it features a mix of plants from the park’s early days, native plants selected by the central park conservancy, and some native and invasive plants that have spontaneously started growing on their own. the habitat is meant to recall olmsted and vaux’s vision of a rural landscape like those in upstate new york and new england.
starting from the glen span arch, follow the path along the south and then the east side of the waterway, and you’ll encounter spurs and bridges that take you right over the water. you’ll find wetland plants like lizard’s tail, jewelweed, and skunk cabbage. the last of these spurs before the final waterfall is where the pumpkin ashes live. or just go here.
maybe part of the reason these trees have hidden in plain sight for so long is the fact that they look really similar to our other ash trees. you’ll be looking for straight trees with gray-brown trunks that have deep furrows, almost looking like dry, cracked soil. pumpkin ashes are so named because mature individuals can swell at the bottom like a pumpkin, but i didn’t really notice this trait on the central park trees. they have compound leaves with opposite, oval-shaped leaflets, meaning each leaf is composed of smaller leaves, pairs of which sprout from the same place on the stem. pumpkin ash leaves usually have 7 leaflets. their twigs are densely fuzzy, almost velvety.
but the easiest way to identify a pumpkin ash is from its flat, papery fruits, called samaras, which are the largest of new york’s ashes. right now, some of the pumpkin ashes are fruiting and scattering their samaras across the ground, making their identification even easier. the pumpkin ash’s samaras measure 2-3 inches long and have a tapered end. other ashes’ samaras are shorter, with the thick seed taking up more of the fruit’s overall length. the common green ash’s samara usually looks pinched at the end and the seed is almost cylindrical.
so, is there hope for these trees? the state has regulations for moving firewood, which is part of how the insect spreads. researchers are actively looking for ways to inoculate the tree, and monitoring trees that survive the infestation with the hope that they might provide clues to create resistance. but right now, the central park conservancy and the city at large simply don’t plant ash trees, instead looking for other more resilient trees that could help fill the niche. the state and other organizations collect ash seeds for restoration efforts in the future, perhaps after we’ve defeated emerald ash borer.
it’s neat that central park’s trees have survived for so long despite the ongoing emerald ash borer infestation, and i was told recently that the sea of concrete in our developed city can insulate some of the city’s trees from pestilence—there are still large elm trees that have avoided dutch elm disease in central park, for example. but i’ve already started noticing evidence of emerald ash borer infestation in some of the green ash trees i encounter on the sidewalk. so i would say that if you have a keen interest in seeing the rarest of new york’s ash trees, you might want to pay a visit soon.
postscript
i feel pretty confident that these were the pumpkin ashes. but it’s a hard identification. and if i’m wrong, well, sorry!
i submitted the draft of my book!!!! as you may be aware, i’m writing an introductory field guide to new york city called wild nyc, scheduled to be published by timber press in april, 2025 (“supply chain,” they tell me) and featuring my writing, lots of my photos, and illustrations from my friend chelsea beck. many of the posts i’ve written for this newsletter have been scrapped material i found while researching, so if you like these posts then you should consider buying the book (…in a year and a half). and while i no longer have my main source for newsletter content, i do have a crap-ton more free time, which i am very excited about.
ps: did you know there’s a secret cross carved into a rock in central park, probably dating back to the war of 1812? if you’d like to know where it is… you’ll have to wait to buy the book. or play the long game and befriend me, get me to join you on a trip to central park, and then nonchalantly drop hints that you’d like to see some ancient stuff. you can also just ask the central park conservancy’s staff where it is, because i actually don’t think i could navigate someone to the spot unless i was actually there with them.
