What is a Black Locust?

The black locust tree, or Robinia pseudoacacia, is native to the southern Appalachian Mountains and the Ozarks. It may grow to be as tall as 80 feet (24 m) in height and is usually not shorter than 30 feet (9 m). This tree grows up to 19 oval-shaped leaflets on each leaf, with each leaflet having a matching pair on the opposite side. In the spring, the black locust tree usually produces flowers that are pea-shaped and typically white or yellow in color. Older black locust trees usually have dark-colored bark, while young trees may have green bark.

Most black locust trees grow naturally in fields, prairies, or patches of woods. These trees do best in well-drained soil and full sunlight, and they tend to prefer very hot, humid conditions. They do not typically spread by seed because the thick outer shell of the seed doesn't germinate easily. Most of the time, new growth occurs as a result of underground rhizomes, also called roots. These rhizomes often sprout more rapidly as a result of any damage, such as tree cutting, fires, or disease, and are considered an invasive species in some areas.

Even though the black locust tree often grows rapidly from the spreading of underground rhizomes, it does not usually live as long as most other trees. The black locust tree cannot compete well for root space because its roots tend to be shallower and weaker when compared to other types of trees. This type of tree may also become weak when living in the shade of other trees because it normally requires full sun for adequate growth. It is rare for most black locust trees to live beyond 100 years. When they are grown under the right conditions, they tend to be hardy plants and can withstand very cold winters and very hot summers.

People who have a problem with invasive black locust trees may be able to control their spreading through either mechanical or chemical control. Some methods of mechanical control include cutting, mowing, and bulldozing. These methods may result in further underground rhizome growth, but spreading hay across the cut area once a year may prevent the seedlings from sprouting. One effective method of chemical control involves applying an herbicide containing glyphosate with a hand sprayer to freshly cut stumps. This method may be most effective during late fall or winter when the tree is dormant.