Deciduous tree to 20m, rough and furrowed bark on trunk and larger branches.
Leaves are thin, bright green with a paler/whitish underside, 15cm long, compound in structure (made up of two or more leaflets attached to the leaf stalk, similar to ferns/some wattles) with 10-20 leaflets in opposite pairs and a single terminal leaflet larger than the others.
Black, hard-coated, in a flat, bean-like pod, 3-8cm long.
Clusters of sweetly perfumed pure white pea flowers in spring.
Once introduced to an area, black locust expands readily into areas where their shade reduces competition from other (sun-loving) plants. Dense clones of locust create shaded islands with little ground vegetation. Lack of ground fuel limits the use of fire in natural disturbance regimes. The large, fragrant blossoms of black locust compete with native plants for pollinating bees.
Southeastern US and Appalachian Region
Along streams, rivers, fields, meadows, disturbed areas, forest edges
Fragrant white flowers appear in drooping clusters in May and June and have a yellow blotch on the uppermost petal. Fruit pods are smooth, 2 to 4 inches long, and contain 4 to 8 seeds. Two other locusts native to the Appalachians, Robinia viscosa (with pink flowers), and Robinia hispida (with rose-purple flowers), are used in cultivation and may share black locust’s invasive tendencies.
Black Locust, 5341035, Jan Samanek, Phytosanitary Administration
Black Locust leaf, 0008365, Paul Wray, Iowa State University
Black Locust bark, 5476650, Chris Evans, University of Illinois