Black Locust

Black locust can grow up to 80 feet tall with a canopy as wide as 25 feet and can live about 90 years. Its leaves are pinnately compound, with each containing 10-20 round or oval leaflets. At night, the leaves on the black locust fold up, and they slowly open again as the sun rises. The tree drops its leaves in the fall and regrows them each spring. 

Reproduction is either asexually by forming suckers (or clones) or sexually via seeds. Clusters of bisexual white flowers that resemble pea flowers bloom in late spring, and these are fragrant and attract many pollinators, such as bees and butterflies. After pollination, the flowers produce pods with four to six beans. These pods start green but turn dark brown as they mature, splitting open and dispersing the seeds.

The black locust is an aggressive species that can suppress the growth of other species nearby through its rapid growth and the production of chemicals that can inhibit the growth of other plants.

The leaves of the black locust contain allelopathic compounds that can be released into the soil by leaching off the leaves during decomposition. Allelopathy is a phenomenon that has both positive and negative effects on other organisms through secondary metabolites that this tree will produce to obtain a competitive advantage over other plants, animals, and microbes. Allelopathic compounds are not the only compounds that this tree produces. It also produces alkaloids, flavonoids, and phenolic compounds that help deter animals from eating its leaves. Those compounds also make the tree resistant to rot and disease. 

*This resource is a product of Dr. Sara Wright’s Plant Diversity course in the Biological and Biomedical Sciences Department.