You may have noticed puffy white flowers on trees around the neighborhood. But these trees are not the beloved cherries; they are the dreaded bradford pear. GM wrote about them as part of his Know Your Trees series and here is that article again:
Today on Know Your Trees, GM explores a tree even worse than the ginkgo: the bradford pear.
Badford pear trees are trees that often get confused for cherry trees since they bloom with poofy white flowers around the same time that cherries do. But they are not cherries, and their flowers are not quite as attractive. They lack the subtle shade of pink and have small green leaves:
Once you realize how to distinguish a bradford pear from a cherry, you realize they are everywhere. Where once you thought you saw street after street lined with cherries, you now see pears.
And if the only distinguishing factor was that the flowers are not quite as attractive as cherries, it wouldn’t be a big deal. But that’s not the case.
Bradford pears are invasive. They were introduced in the 1960s as a sterile ornamental tree. But they turned out not to be sterile. And they started to spread like wildfire.
And the worst thing about bradford pears is that they grow so fast that their limbs are extremely weak and fragile. There was a lovely row of them on GM’s block a while ago, but after every slightly serious storm, the street would be littered with broken boughs. And the trees only have a lifespan of 20-25 years, which is extremely short for large trees.
It’s for this reason that you can find plenty of people who want to cut them all down as fast as possible. Here’s a writer for USA Today advocating as much:
When you see those fields of white flowering trees, please don’t get giddy with excitement over pretty white flowers. What you are looking at are Callery pears destroying nature. Callery pears have 4 inch thorns. They can’t be mowed down. Those thorns will shred John Deere tractor tires. They can only be removed by steel tracked dozers, decreasing the value of agricultural or forest land to the tune of $3,000 per acre.
There are some bradford pears around Georgetown. And they probably should come down, just like the row on GM’s block. It’s sad to cut down a mature tree, but think of it as just getting to the point where you have the next tree mature all that much faster.
The Georgetown Metropolitan 
The question is how Bradford pears ever came to be planted as street trees or anywhere on public property in Washington. Did DDOT’s Urban Forestry Division or the Department and Environment plant them before their disadvantages were widely known? Or were they planted without authorization on public property by well-intentioned businesses or private citizens? Whatever the origin of their planting in public spaces, they do appear to spread as “volunteers,” notwithstanding their billing as “infertile” cultivars. Another invasive species (q.v. bamboo) for our urban forest is the last thing Washington needs.
There have been some other issues with Bradford Pears worth considering