It sprouts prolifically from root runners and can become a nuisance. This tree, like redbud, is a legume, hence the fruit is a flat pod 3 to 4 inches long, remaining on the tree though winter. The black, bony seed inside the pod is eaten by squirrels. The leaf is compound, having from 7 to 19 entire leaflets which are alternate, light green above and pale green underneath. Branches are armed with a pair of short, sharp spines located at the base of each petiole.
Mature bark resembles black, twisted rope.
Locust flowers form pendant clusters of honey-sweet white blossoms, spreading a fragrance of heavy perfume in late spring. Because of the sweet flower scent, some people confuse this with its relative, the honey locust. Honey locust gets its name from the honey-like pulp of its large pods, often 12 to 18 inches long. It is easily recognized by long, wicked thorns located on the trunk and branches. Insulator pins and fence posts have been made from black locust becuase of its resistance to rot.