Some different varieties of locust trees include honey locust, black locust and the African locust bean tree. All of these trees are in the Fabaceae family and are related to the sweet pea.
The black locust grows in the central and eastern parts of the United States and does best in hardiness zones 3 to 8. It usually attains heights of between 30 and 50 feet with a 20- to 35-foot spread. In mid-spring, it produces racemes of beautiful, fragrant white blossoms that attract beans and mature into long pods. The black locust prefers soil that is dry to medium but well-drained and can survive drought. Because it can also tolerate air pollution, it is often planted in cities.
The honey locust is similar in size to the black locust and can also tolerate poor growing conditions as long as it is planted in full sun in zones 3 to 8. It is notorious for its thorns, though thornless varieties such as F. inermis are available. The greenish-white flowers are less showy than those of the black locust, but the tree gets its name from the sweet substance found in its pods.
The African locust bean tree is native to west Africa east to Uganda, and like the honey locust is known for the sweet pulp in its pods. Many people eat the seeds and use them to make spices.