AppearanceRobinia pseudoacacia is a deciduous tree that, while native to parts of the United States, has spread to and become invasive in other parts of the country. Trees grow from 40-100 ft. (12-30 m) in height. Trees grow upright in forests, but develop an open growth form in more open areas. The bark of black locust is light brown, rough, and becomes very furrowed with age.Foliage Leaves are pinnately compound with 7-21 small, round leaflets per leaf. Leaflets are 1.5 in. (4 cm) long. A pair of long, stipular spines is found at the base of most leaves. Flowers Flowering occurs in the spring, when showy, fragrant, white to yellow flowers develop in 8 in. (20.3 cm) long clusters. Fruit The flowers give way to a smooth, thin seed pod that is 2-4 in. (5.1-10.2 cm) in length.Ecological ThreatRobinia pseudoacacia is native to the Southern Appalachians, the Ozarks, and other portions of the Midsouth, but is considered an invasive species in the prairie and savanna regions of the Midwest where it can dominate and shade those open habitats.