Tree-of-heaven, Ailanthus altissima, is a beautiful name for a pest tree. I have heard it is one of the few species illegal to plant in Indianapolis, due to its tendency to spread aggressively via seed. Male and female flowers are borne on separate plants. Single female trees can produce thousands of wind-borne seed.
It is a native of Asia where it apparently got its common name from growing so fast to reach heaven. Twigs have the density of balsa wood. I use them to help students learn to recognize the characteristics of twigs, like leaf scars and bundle scars, because these features are so large on Tree-of-heaven.
This tree is the one immortalized in the book A Tree Grows in Brooklyn and, indeed, I did see if growing there when I spoke at the Brooklyn Botanical Garden this spring.
Tree-of-heaven can grow quite large. There is one in a backyard across from Binkley’s on College at Kessler
Ave. that my husband and I see every Monday late afternoon during discount draft day. Even in this dry summer it had an impressive display of flowers and seeds.
The plant also sends up multiple shoots from the same rootstock, resulting in patches.
Tree-of heaven is one of 30 trees featured on the Butler University tree walk. For more a brochure or more information on the walk, visit www.butler.edu/herbarium.