Know Your Trees: London Plane Trees

Today for Know Your Trees, GM is going to talk about a new superstar for Georgetown street trees: the London plane.

The first thing to know about London plane trees is that they look an awful lot like another tree you see a lot in North America: the sycamore. And that makes sense, since the London plane is a hybrid of the sycamore.

And the way GM was taught as a child to identify sycamores applies just as well to London planes: they look “sick” (as in “sick-amore”). What that meant was that the bark has a distinctive look like this:

This mottled appearance does not actually indicate sickness. But you get the drift.

Planes and sycamores also have distinctive leaves. They are about the largest you’ll find on a street tree and look somewhat like massive maple leaves:

The trees are also known for their fruit, which looks like these fuzz balls:

So why talk about London planes instead of sycamores? Generally London planes are more frequently planted as street trees than sycamores. They are incredibly hardy both to heat and cold. And they grow like gangbusters.

GM has tracked the growth of a London plane on his block. When he first moved to this block six years ago, it was just planted and looked like this:

(yes it’s the tree that’s barely a twig at the center. A child could wrap one hand around the trunk).

Here’s what that same tree looks like four years later:

It’s probably about four feet taller now. And the trunk is at least ten inches thick. At full maturity, London planes can be over 130 feet tall with a trunk over 3 feet thick.

This is a tree perfect for the new weather Georgetown now has. As traditional species like maples or ash die away from either global warming or infestations, new superstars like the London plane tree can quickly provide a beautiful canopy ready to survive the new conditions.

London plane trees got their name, not surprisingly, from London where they have long lined the city’s boulevards and park pathways:

If left along, London planes grow with a distinctly triangular shape. However, a practice known as pollarding can dramatically change that shape. This practice, popular in Europe, involves pruning the trees aggressively to prevent the trees from growing too large. It gives them a spooky look in the winter that makes it look like they’re dead:

This practice is not followed in DC very often (except for crepe myrtles, but that’s a story for another week).

Notwithstanding its star role in new waves of Georgetown street tree plantings, eventually there could be too many plane trees here and the plantings will slow down. Regardless of how well suited a tree is to its environment, its bad to have too many of one species in an area. American elms were once perfectly suited to streets in places like DC. That is until the Dutch elm disease showed up and they almost all had to come down. New York City has already hit that point with London plane trees (they are everywhere  there) and prohibits any new plantings. We’re not there yet for Georgetown, but we will be eventually.

GM also wants to take a moment to mention the great work the Trees for Georgetown does. Last night they held their annual garden party:

It was a great time! Hopefully you can join us next year!


1 Comment

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One response to “Know Your Trees: London Plane Trees

  1. Betsy


    Am loving your tree series. And thanks for the plug for TFG and party pictures. Hope you had a good time!


    Sent from my iPhone


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