black locust
Robinia pseudoacacia L.


Robinia 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.
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.
Flowering occurs in the spring, when showy, fragrant, white to yellow flowers develop in 8 in. (20.3 cm) long clusters.
The flowers give way to a smooth, thin seed pod that is 2-4 in. (5.1-10.2 cm) in length.
Ecological Threat
Robinia 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.


Selected Images


EDDMapS Distribution

EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit

State Regulated List

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Rosidae
Order: Fabales
Family: Fabaceae (Leguminosae)
Genus: Robinia
Subject: Robinia pseudoacacia L.

Synonyms and Other Names

Other Common Names:
false acacia, yellow locust


Plants - Hardwood Trees