Understanding which properties a locust tree exhibits, such as leaf type, bark color, height and fruit type, is essential to identifying which specific tree it is. Locust trees are highly adaptable and can be easily transplanted. They are commonly planted in urban environments due to their hardiness and tolerance of pollution and other harsh conditions.
The black locust and honey locust are the two most common locust trees, and both are native to North America. Each have unique characteristics that aid in their identification.
Black locust is characterized by a deeply furrowed, light-gray bark. It has a trunk width of 1 to 2 feet, and it grows to approximately 80 feet tall. Twigs on its branches commonly grow spines or thorns. Its leaves are bluish-green, and pinnately compound, meaning each leaf stem contains multiple paired leaflets. There are usually seven to 18 leaflets on each leaf stem. Leaves grow from 6 to 12 inches long, and they fold up at night. These trees grow small, pear-shaped flowers. Each flower has five white petals, growing in clusters that are 4 to 8 inches long. Black locust is also commonly called false acacia.
Honey locust trees have a relatively smooth, reddish-brown bark, which breaks into long, thin, vertical ridges as the tree ages. They commonly grow from 70 to 80 feet tall. The branches grow four or more thorns on average and have greenish- and reddish-brown twigs. The thorns grow from 4 to 8 inches long. The tree has compound leaves, much like the black locust, as well as double compound leaves. Each leaflet on the stems grows to be 3/4 to 1 1/2 inches long.