The Bradford Pear (Pyrus Caleryana) is on the invasive plant list in many states, including Tennessee. If you have any doubt about its invasiveness, just pay attention in the next week or so to the abundance of trees with white blossoms you see everywhere. True, they can be lovely in full bloom, especially when planted along a driveway or parking lot like this:
But you may not realize that these trees are aggressively seeding themselves all over the area, crowding out native vegatation. Today I passed through Lakeland in the I-40 and Canada Road area. Along both the interstate highway and Canada Road, Bradfords are blooming everywhere: on slopes along the road, on entrance and exit right-of-ways, and in the woods and fields along the roads. I pulled off Canada Road to snap the picture below of an undeveloped area in Lakeland where "volunteer" seedlings have taken advantage of a fallow area to establish a forest of Bradford pear trees. (And I might mention that this was a very stinky place. If you've been downwind of a Bradford in full bloom, you know what I mean.) Unfortunately, I could have taken a similar picture at any of a dozen or more places along my route.
So where did all these trees come from? Twenty-five years ago, Bradfords were a favorite in new housing developments because they are beautiful, fast-growing trees. It wasn't until the trees reached maturity that it became apparent that the weak, branching-trunk growth habit of these trees made them literally fall apart as they matured. The slightest wind (sometimes no wind at all) will cause huge sections of the trunk to split away, and they have an uncanny tendency to land on houses or cars or people.
Then, as new cultivars were developed to counter the weak branching problem of the Bradford ('Chanticleer', 'Aristocrat', and others), they cross-pollinated with the older varieties and became prolific re-seeders. Whether these new cultivars will correct the problem, remains to be seen.
So don't be fooled by the beauty of these trees. The fact that they are crowding out our native trees is not the only reason to avoid them. It's just the most noticeable reason at this time of year.