Black Locust
Robinia pseudoacacia · Deciduous hardwood
Plant Family
Fabaceae
Tree Category
Shade Tree / Forest Tree
Variety / Cultivar
Species type (Wild type)
Hardiness Zones
Thrives in USDA Hardiness Zones 3 through 9, demonstrating high adaptability to a wide range of continental and temperate climates.
About This Tree
A medium to large deciduous tree with an irregular, open crown, often growing with multiple trunks or suckering to form thickets. Known for rapid early growth, brittle branches, and deeply furrowed, rope-like bark.
Leaf Characteristics
Alternate, pinnately compound leaves ranging from 8 to 14 inches long, containing 7 to 21 oval leaflets with smooth margins. Leaves emerge bluish-green, turn dark green in summer, and show minimal yellow fall color.
Bark Characteristics
Dark brown to gray bark, deeply furrowed with prominent, interlacing ridges that often form a cross-hatched, rope-like pattern. Twigs typically feature paired sharp spines at the nodes.
Growing Information
Origin Region
Native to the southeastern United States, but widely naturalized across North America, Europe, and Asia.
Growing Season
Leafs out relatively late in spring with bright green foliage, produces fragrant white flowers in late spring, matures seed pods by autumn, and enters winter dormancy.
Sunlight & Water Needs
Requires full sun for optimal growth. Highly drought-tolerant once established and adapts well to poor, dry, or disturbed soils, preferring well-drained conditions.
Mature Size
Typically reaches 40 to 80 feet in height with a spread of 20 to 50 feet. Fast growth rate when young, with a moderate to short lifespan due to susceptibility to wind damage and borers.
Special Characteristics
Extremely hard, rot-resistant heartwood making it valuable for fence posts and outdoor construction. Features nitrogen-fixing root nodules that enrich the soil, and significant drought and urban pollution tolerance.
Wildlife & Ecology
Highly attractive to pollinators due to abundant nectar-rich flowers. Seeds and pods are consumed by various wildlife, and the dense thickets provide nesting cover for birds and small mammals.