A black locust
The leaf and flower of a black locust
|The deeply furrowed bark of a black locust
Scientific Name: Robinia pseudoacacia
Hardiness Zones: 5 to 8
Height: 40 ft
Spread: 25 ft
Type: deciduous tree
Annual Growth Rate: more than 18 inches
Black Locust is hard wooded, grows best in a sunny location and tolerates any soil that isn't swampy. This hardy tree is a legume and has a suckering root system that forms thickets if not controlled. The fragrant, white flowers appear after the leaves and are borne in drooping clusters. The fruit is a brown pod and the bark is coarse and fissured.
'Bessoniana' - A thornless cultivar with a compact oval form that will be 30 feet tall and 20 feet wide.
'Frisia' - The tree has bright yellow summer foliage color.
'Inermis' - A rounded tree with thornless branches. 'Lacy Lady' (Twisty Baby TM) - This 8-foot tall plant has crooked stems and curled foliage.
'Purple Robe' - The new growth is purplish and the flowers are dark purple.
'Pyramidalis' - This cultivar is tall, narrow, and spineless. The plant will be 40 feet tall but only 15 feet wide.
'Umbraculifera' (Globe Locust) - A dense, globe-shaped head on a tree only 12 feet tall and wide, rarely flowers.
Text courtesy Michigan State University Extension