For the last few weeks, as mentioned in some previous posts, I've been helping the New York City Parks Department code some of the correspondence they receive from the public (mostly complaints) for future analysis. Luckily, not all of the communiqués are complaints; some get coded as "appreciation." These mostly resemble something like "CITY JUST CAME AND PLANTED NEW TREE IN FRONT OF HOUSE THANK YOU SO PRETTY!" (Sometimes there's an amusing little dig tacked on the end, like, "BUT WOULD HAVE LIKED A CHERRY TREE BETTER.") There are also a few obscure inquiries from beyond the city limits. One of my favorite of these was from a former tourist, who wrote something like, "I've just arrived home from New York and am wondering -- what's the name of that tree I saw everywhere with the camouflage bark?"

This made me smile because, although it's an imaginative description, I knew exactly what she meant: "that tree with the camouflage bark" is the perfect way to describe the London plane tree -- which is, indeed, its name (as a Parks Department employee informed her in a polite letter).

Ah yes, the London plane tree. Once you notice it, you notice that it's everywhere. In my own neighborhood in Brooklyn, the streets are lined with dozens of them, mostly biggish ones straining against their tiny old-regulation-size tree pits (new tree pits are considerably larger, much to the distress of a few homeowners). Some beautiful London planes tower over parts of the Columbia University campus. Fort Greene Park in Brooklyn has some of the biggest ones I've seen in the city. (I don't claim they're the biggest out there, just the biggest I've seen.) I recall another beauty by the parade grounds in the Bronx's Van Cortlandt Park. They are lovely, with their big leaves and wide canopy, and their impressively massive trunks covered in that distinctive smooth mottled bark.

They are also very important to the city of New York (and not just because the leaf is the Parks Department logo). The London plane, usually considered Platanus x acerifolia but also known by other Latin epithets, is not really native, although it very closely resembles the native American sycamore, Platanus occidentalis. Actually, it is probably a cross between this American species and Platanus orientalis, a Eurasian relative. In any case, it has been widely planted as a city tree for decades, which turns out to be a good idea. In its assessment of the New York City urban forest, the US Forest Service Northern Research Station determined that the London plane is the most important city tree we have.

They base this conclusion on several factors. For one thing, London planes have a very high leaf area per tree; that is, the London plane gives us a lot more pretty, shady, air-filtering, evaporatively-cooling leaves per single trunk than most other species in the city. In fact, according to the Forest Service, London planes make up just 4% of the city tree population, but represent 14% of the city's total leaf area. (Compare this with the virulently invasive tree of heaven [Ailanthus altissima], which constitutes 9% of the tree population but only about 4% of the total leaf area.)

Also, because they tend to become very tall and have large canopies, London planes are our best trees for carbon storage and sequestration. They are holding on to about 185,000 tons of carbon (14% of the total urban tree carbon pool), and each year they sequester another 5,500 or so tons (about 13% of all the carbon sequestered by city trees each year). That makes them both gorgeous and highly beneficial: all in all, good trees to have around.

Personally, though, I think the bark looks more like a jigsaw puzzle than camouflage.