A friend recently wrote:
I have a quick tree question: what kind of tree are all those fallen pods coming from that are now on the sidewalks of Williamsburg? There's a ton near us. The pods are turning black, maybe rotting? (They don't seem to smell, but then again it's freezing out.) I'm just curious about the name of the tree. The sidewalks around Graham Avenue are covered with pods.
I would guess you have a bunch of honeylocust trees around you. They have compound leaves comprised of small leaflets that turn a nice golden color in the fall before showering the pavement. The seed pods come after, from October through Dec/Jan and are dark brown to black, roughly 4-8" long, rather curved by this point. The pods hold good-sized round seeds, also a dark color. Does that sound right? They were a popular street tree planting years ago because they were able to cultivate a thornless variety (aka the ones you see, Gleditsia triacanthos var. inermis) - the regular species in the wild has serious 2" thorns that cover the branches. What everyone realized after the fact is that they are also pretty shallow rooted trees so now where you find a honeylocust as a street tree you also tend to find heaved up pavement. (potentially another ID characteristic for us urbanites). The botanical name is Gleditsia triacanthos, but obviously most people know them as honeylocusts.
Apparently I got it right:
Thanks for all this info! I just looked up images of honeylocust trees and that's exactly it! There are a ton of them in Williamsburg, and you're right about the sidewalks.