India, Oct. 19 -- The tree-of-heaven has a lovely name and a rough reputation. According to a U.S. Forest Service species review, it first arrived in Pennsylvania in 1784 as an ornamental plant. Today it grows in places from Maine to southern California, and has infested hundreds of acres of oak-hickory forest in Shenandoah National Park in Virginia. So how did a tree planted for looks become a forest problem?

This tree species is native to central China and Taiwan. The review says that the distribution of this tree in North America seems to have occurred through three different introductions from China. Pennsylvania introduced it in 1784, while New York used the tree for ornamental purposes in 1820. The eastern introductions came throug...