The turning of the leaves in Dublin and London seems to be less spectacular than in the US, but there’s no question that autumn is here. In London, we stopped to admire a particular kind of tree by Constitution Hill in Green Park.
It was similar to many trees in Dublin, and it also looked very much like a tree that Anita admired in Philadelphia last year. We were both drawn to the unusual bark of a tree near Independence Hall.
I think I know what kind of tree we saw: London plane trees. Given the apparent age of the tree in Philadelphia, however, it’s probably an American sycamore. They’re both remarkable trees, beyond their obvious beauty.
The London plane tree is a type of sycamore that was especially popular with Victorians in London. Given the smog over London at that time, it was one of the Victorian fads that made sense. Maybe it was the obvious choice for a city tree because all the others kept dying in the miserable environment.
The unique look of its trunk is due to the fact that the London plane tree sheds its bark. When the soot of London clogged the pores of these trees, the trees shed the old “skin” and revealed new bark with clear pores. (The photo on the right is the tree in Philadelphia, for the nit-pickers in the audience.)
Sycamores have distinctive fruit, of course. They have two more special features: their young leaves are hairy and their mature leaves are large and waxy. In suburban environments, these features seem like disadvantages, because the hairs aggravate allergies when they fall off in the spring. And the large leaves take forever to rot away.
But in polluted air, the springtime hairs trap airborne pollutants and keep them out of human lungs. The hairs fall to the ground when the leaves mature, escorting the particulates to the sewer system. Later in the year, the mature waxy leaves provide acres of surface area to collect dust and soot, and they rinse clean in the rain. In other words, the London plane tree is ideally suited for scrubbing the air of large-particulate pollution — the original London fog.
So, it’s not just another pretty tree.
2 Comments to “London Plane Trees”
17 October 2007
I am truly fascinated by the dendrology/history lesson. Thanks for sharing!
18 October 2007
I saw these same trees in France (especially in the south around Nice) a few years back & found them fascinating. Though I did not take the time to do the research behind it. To me the bark on the trunks looked like camoflauge. Which I guess is the whole point of camoflauge to look like nature. I just wasn’t sure what the trees were hiding from since they can deal with the environmental issues all by themselves. I bet they just call them Sycamores in France.