Problem Plants

Nativeness, Biodiversity, and Urban Flora in the Anthropocene

As I wrote last week, winter in Bushwick can look and feel pretty bleak. Dirty ice, frozen garbage, and soggy dog shit line the sidewalks, while sparrows and pigeons pick at frosty french fries and arroz con pollo in the gutter. The carcasses of last season’s spontaneous plant population (the weeds), shriveled or turned to mush, linger in heaps along the edges of vacant lots and in untended street tree pits.

Bushwick in winter (photo by Dan Phiffer)

But I know that there is life buried in Bushwick’s frozen soil, and that keeps me scheming and planning through the winter months. As the weather warms and the days lengthen, dormant roots will stir and a plethora of seeds will begin to germinate, leading eventually to the riot of green that inhabits Bushwick’s marginal spaces in mid-summer. But for now I wait, think, and plan.

Bushwick’s Summer Flora (Troutman St. between Wyckoff and Irving)

Last night I had the chance to convene a gathering of like-minded folks: other plant nerds also sitting in wait, anticipating the return of our urban verdure (after the proper and seasonally appropriate freeze, of course!). This gathering of plant fanciers was part of a closing celebration for the Center for Strategic Art and Agriculture, a Bushwick-based gallery, event space and garden that hosted my Invasive Pigments project as its final exhibition. Founded by Lorissa Reinhart at The Silent Barn, the Center has functioned for the past two years as a wide-ranging, richly programmed experimental art, theater, music and gardening venue. I’ve benefited immensely from working with the Center, cultivating my first Invasive Pigments garden, holding workshops, tours, an exhibition, and finally last night’s event, a panel called “Problem Plants: Weeds in Ecology, Art and Culture”.

A view of the CSAA panel from the audience (Thanks to Giada Crispiels)

The speakers on last night’s panel hailed from a range of disciplines, from tropical ecology to sculpture to theoretical biology. Dr. Amy Berkov gave a us funny and fascinating look into the milkweed/beetle saga that is ongoing in her LES community garden plot, while Anne Percoco showed us intriguing images of her public projects engaging marginal, plant-infested urban landscapes from Jersey City to Bangalore, India.

Anne Percoco’s larger than life wheat-pasted-weeds

Dr. Sasha Wright waxed poetic on the benefits of biodiversity from a theoretical perspective (she even had us loving her graphs!), and Miriam Simun held us rapt with an account of her search for the federally protected Agalinis acuta flower, which blooms just one day a year. The Q + A was packed with relevant questions and comments, and left me hungry for more of this sort of dialogue. I heard the same from the mixed audience members, who ranged from urban gardeners and food justice organizers to environmentally involved artists and curators, landscape architects, art students, and curious neighbors. It was refreshing to jump beyond the binaries of art/science, technology/living systems, native/exotic, and even more refreshing to have the panelists and audience right there with me.

A sphinx moth feeding on milkweed in Amy Berkov’s garden plot (photo by Amy)

The panel planning and the discussion last night has pushed me to take a look back at my own projects. Reviewing my Invasive Pigments project reminded me to finally consider some of the data I’ve gathered on the plants I’ve been working with, and to make some comparisons with other data sets. Admittedly my sample size is small and my methodology somewhat unorthodox, but the results still have me thinking.

collecting and distributing urban dirt

First, a little background: back in early March of last year, I went on an urban soil prospecting and collection trip. I visited eight sites around Bushwick where I’d seen diverse spontaneous plant populations in previous growing seasons. Armed with a trowel and quart-sized mason jars, I dug up frozen, seemingly lifeless dirt and transported it to the CSAA garden, where I laid it out on the rich soil remaining from last year’s vegetable garden. Come April the beds began to come to life, sprouting a good mixture of volunteer vegetables and hardy urban weeds. Over the following months most of the vegetables and herbs were out-competed by the voracious weed population that eventually towered more than twelve feet above the beds (although the cherry tomatoes gave everyone a pretty good run for their money).

The Invasive Pigments garden in mid-July

I kept careful track of the range of species that popped up in the garden, watching as they sprouted and found their niches, some climbing up ropes and poles (hedge bindweed, false buckwheat, mile-a-minute weed) others leafing out in the understory (asiatic dayflower, pokeweed, black medic), while the fast-growing surged into a canopy (common lambsquarters, red root pigweed, devil’s beggarticks) and the early pioneers (sheperd’s purse, dandelion, crab grass) succumbed to shade and dwindled away.

Mile-a-minute weed (Persicaria perfoliata) climbing skyward

As the growing season drew to a close in late October, I tallied up the species numbers and sorted them by the conventional native/non-native binary used in other studies of New York City Flora: thirty-two species total, ten of which are considered native, with the remaining twenty-two falling into the non-native category.

After some internet research, I’ve found that my numbers are almost exactly flipped from the most comprehensive large-scale study done in recent years*, DeCandido et al.’s A first approximation of the historical and extant vascular flora of New York City: Implications for native plant species conservation, published in 2004. (*that I’ve found, anyway. Know another? Let me know!).

Stats from my slide presentation last night

At first I was puzzled by the discrepancy between our numbers, but digging into the methodology of the DeCandido study, I discovered that we have a fairly different understanding of where one might go to find the “wild urban flora” of New York City. DeCandido and his team focused on parks greater than 40 hectares in size that also contained a significant amount of “natural area”, with a natural area defined as “one that is composed mostly of unmanaged vegetation.” I also work with “unmanaged vegetation”, but the population I’m focused on doesn’t live in parks or “natural areas”, but sprouts from the cracks in the sidewalk, the rubble of vacant lots, and the rich pools of muck around edges of storm drains. While city parks are fragmented and disturbed compared to the pre-colonial landscape (which was managed by humans, just very differently!) the everyday urban streets bear scant resemblance either of these hallmarks of “naturalness”.

Two “unmanaged” landscapes: Ailanthus habitat in Bushwick and the Central Park Ramble (thanks Flickr user jon.t)

The DeCandido study also found that New York City (the five boroughs combined) has lost more than 40% of its native plant population. Brooklyn (Kings County) has the lowest species diversity of any borough (just 695 of the 2177 species found in greater New York City) and has lost 75% of its native species. Additionally, Brooklyn lacks the larger parks found in Staten Island, the Bronx and Queens (Marine Park, Brooklyn’s largest park, is half the size of the largest parks found in the other boroughs). If we insist on eradicating or “controlling” the non-native plant population that fills our streets, we’ll be eliminating the bulk of the biodiversity that our plant-impoverished borough has to offer. This tells me that it’s high time we embraced our exotics, non-natives, interlopers and escapees. As Peter Del Tredici suggests in his indispensable “Wild Urban Plants of the Northeast: A Field Guide”, these plants have become the “de-facto native vegetation” of our urban environments, and considering all the benefits that urban greenery brings (from the built environment to mental health), we’re going to need every one of those meddlesome, aggressive species as our climate gets less stable.

As it happens, during the panel last night, Sasha (building on ideas introduced in Amy’s milkweed talk) went to great lengths to back up this argument for non-native species with data! She stressed that the presence of non-native species does not inherently lower species diversity overall (while acknowledging that in extremely rare cases, unusually aggressive species like the infamous Kudzu can require human intervention). She showed us the results of a range of ongoing studies that have found that plant communities with a mixture of native and introduced species actually have higher overall species diversity and are more resilient in the face of habitat disturbance.

From Sasha’s slide presentation (via Sax & Gaines, 2003)

This especially makes sense in an urban setting like Bushwick. Plants growing in Bushwick 400–500 years ago have had a very hard time adapting to the new environment we’ve created for them. Dominated by impervious surfaces (streets, parking lots, buildings, sidewalks), the low quality soil they grow in is leached full of a range of pollutants and compressed by construction, foot and vehicle traffic. This soil is embedded in an environment defined by highly variable microclimates (wind tunnels and heat islands) and infested with an invasive species that more than often wants them dead or cut into hedgerows. Plants like Miriam Simun’s darling Agalinis acuta don’t stand a chance in this environment, so they’ve retreated to the outskirts, where they continue to dwindle as strip malls and beach front homes sprout in an ever widening circle around the City.

The diminutive Agalinis acuta on Simun’s fingertip (from Agalinis Dreams)

The non-native interlopers who’ve taken up residence in the harsh urban environment of Bushwick aren’t pushing out native species, they’re filling empty niches. Adapted to difficult conditions, with flexible reproductive habits and opportunistic growth patterns, these urban plants are much better-suited to living side by side with Homo sapiens, despite our indifference to (or even aggressive dislike of) them.

Thus, I’ve come to think of the plants with whom I share the streets of Bushwick as companion plants for the Anthropocene. While we don’t cultivate them knowingly, the way we might a prize rose bush, we’ve set up the conditions that facilitate their growth, and we are now bound together, coevolving in an increasingly volatile environment.

When a street tree dies in Bushwick…