Leaves of black locust | Photo credit: Larry Korhnak, University of Florida
Black locust is a legume - meaning that its root nodes work in concert with bacteria to fix nitrogen from the atmosphere into the soil. These soil nitrates are then usable by it, as well as other plants.
The black locust has a native range in the United States, yet has been transplanted in many states outside of this range, as well as in Europe, southern Africa, and Asia. It is capable of having invasive abilities, and has become a pest in some of these areas.
The specific epithet for this species means "false acacia." Black locust looks very similar to trees in the genus Acacia, which are also in the pea family (Fabaceae).