NY Biodiversity at AMNH

Today I attended Living with Nature: A Conference on Sustaining the NY Metro Region's Biodiversity Through Local Action at AMNH. Co-sponsored by the NYC Soil & Water Conservation District, the agenda had panels on education, arthitecture and green cityscape, food systems, consumer choice, transportation, and natural systems.

I missed the keynote addresses, but heard that Al Appleton was excellent. The architecture panel was great (except for the one who was incredibly lack luster. We shan't name names). As I expected, there was a lot of talk of greenroofs. The Gaia Institute has one in the Bronx using native plants. But really, all the greenways and greenroofs won't provide habitat for shade-tolerant forest herbs. So it's not all about building. You can't construct your way out of land conservation.

I sat in on the natural systems panel in the afternoon. It was excellent as well. The DEC representative was especially lively and made several good points...nature does need a Madison Avenue marketing campaign! Carolyn Summers exclaimed that there should be "no more extirpations"...brava!

New shrub in Fort Tryon

Today I was in Fort Tryon Forest, northern Manhattan. Most people know the garden, but there is also a woodland that hangs over the Henry Hudson Expressway, just south of Inwood Hill Park.

This is one of those sites where there weren't a lot of existing records, because on a casual walk through I got 52 new listings. The most exciting was yellowroot (Xanthorrhiza simplicissima), because this species is new to City records. The shrub has deep green, pinnately divided leaves, that sprout in a tuft. It flowers in early spring, with many tiny purple flowers in drooping racemes. (And yes, it does indeed have yellow roots). The plant is not native to New York City, its range is south and east, from Pennsylvania to Florida.

Will the real Aralia elata please stand up?

Japanese angelica tree (Aralia elata)??? Nice fall color, which I have never seen on (& reported doesn't exist for) the ubiquitous other Aralia.

Japanese angelica tree (Aralia elata)??? with infructescence

Devil's walking stick (Aralia spinosa)???

Welcome to the world of botanical taxonomy. For your entre, I thought we would go right for the jugular. Devil's walking stick (Aralia spinosa) is native to the U.S. Most literature cites its range as Delaware & south (e.g., Gleason & Cronquist). One (Mitchell & Tucker) says it's native to New York State. So I called our state botanist who assured me that G&C was right, it is not native to NY. In fact, field work has shown that there is no A. spinosa in the state at all. Everything we have been seeing is actually Aralia elata, an exotic invasive. There is a population of Aralia spinosa out on Long Island, but that was shown to have piggybacked in on nursery stock from North Carolina.

So when a colleague of mine called me to say he had found an interesting Aralia, I was excited. To compare, we began with the familiar.

We went to Highbridge Park in northern Manhattan. There was a small cluster of less than 10 shrubs in an opening in the forest canopy, not far off a trail. This is the Aralia shrub that I see all over NYC. It had dark green leaves held at almost a 90 degree angle to the main stem. We were calling this "spinosa" based on the leaves - veination (joined before margin) & finely toothed, no obvious pubescence. The fruit panicles no longer held berries & had already whithered, so we didn't take a sample.

Now, the fun part. Next we went to Fort Washington Park, a subset of Riverside Park in northern Manhattan (around 158 St.). There were maybe 5 shrubs scattered along a stretch between a trail & fencing for the Metro North train line (so not obviously colonial like above). These plants were new to me - I had never seen this species before. We were calling this "elata" based on the leaves - veination (run to margin), broadly toothed & obvious pubescence. Additionally, these leaves were lighter green & held at a more acute angle to the midstem.

So we sent the samples to Brooklyn Botanic Garden - I could barely get to sleep that night, I was so excited to hear back what the new-to-me plant was. Apparently they think they are both the same species...Aralia elata. They said what they really need is the point at which the inflorescence attaches to the main stem - that is the critical piece distinguishing one from the other. Oh. We didn't get that. But still, sometimes I think taxonomists are too by the book. Can't you just tell which is which? If I can ID species with just basal leaves, I expect a little more info when I provide such bounty.

And so the mystery continues..........
OK, OK, I know. Don't go by leaves. Flowers/fruits are more stable, & so the basis of taxonomic determinations. But c'mon - these have to be two different species. (And additionally, if you aren't supposed to look at leaves, then why the difference between Smilax herbacea & S. pulverulenta (NYS rare) - the former has no hair on it's leaves, the latter has hair. Be consistent, people!)

Blunt Cliff Fern in Harlem


Blunt cliff fern (Woodsia obtusa) festooning the Metro North train trestle in Manhattan. This fern is native and uncommon in NYC.
The ferns are back! Blunt cliff fern (Woodsia obtusa) is growing quickly and by August should be nicely carpeting the sides of the Metro North train trestle that runs along Park Avenue in Spanish Harlem. This fern first came to my attention when I started my job 4 years ago. I walked under the trestle on my walk from the 103 Street 6 train to my office, all the while wondering what species they were but never stopping to look...until finally I did. Woodsia obtusa is not a common plant in NYC. Yet here they were, overwhelming the walls along Park Avenue.

Finally, the following year I did a floristic survey and found that within the mortar of this structure a unique plant community exists, including four fern species that are rare in the City.

Brief history - the trestle extends from 110 to 101 Streets. This portion is constructed of stone and was built in 1870. The mortar was created out of the rock, soil, timbers and various mining debris from creation of the rail tunnel under Park Avenue. Suitable fern habitat was created as these materials weathered and seeps were formed.


Close up of Woodsia obtusa

Surveys found 43 plant species. Whether native or exotic, the majority of the other plants present in the plots were weedy species more commonly found in marginal areas like vacant lots and roadsides. Five ferns were found, including sensitive fern (Onoclea sensibilis), a common wetland species, able to survive do to water pooling in the masonry. The other four are rare in NYC: ebony spleenwort (Asplenium platyneuron), walking fern (A. rhizophyllum), purple cliff-brake (Pellaea atropurpurea) and blunt cliff fern (Woodsia obtusa), are typical of cliff habitats. At approximately 30 feet tall, this trestle acts as a Manhattan cliff.

If one looks carefull around the perimeter wall of Central Park, you will find both blunt cliff fern and ebony spleenwort.