Black Locust
Robinia pseudoacacia · Deciduous Broadleaf Hardwood
Plant Family
Fabaceae (Legume Family)
Tree Category
Shade Tree, Flowering Tree, Timber Tree, Nitrogen Fixer
Variety / Cultivar
Wild Type / Standard species
Hardiness Zones
USDA Zones 3 through 9; highly adaptable to extreme temperatures, poor soil conditions, and urban pollution.
About This Tree
A medium-sized deciduous tree with a deeply furrowed bark forming interlocking diamond patterns, lightweight compound foliage, and pendulous clusters of fragrant white pealike flowers followed by smooth brown seed pods. Fast-growing and tough, often forming thickets via root suckers.
Leaf Characteristics
Pinnately compound leaves 6-14 inches long with 7-19 oval, smooth-margined leaflets. Blue-green above, paler beneath; turns yellowish green in autumn before falling early without dramatic coloration.
Bark Characteristics
Thick, dark gray to reddish-brown bark, deeply broken into heavy, rounded, interlacing ridges and deep furrows, creating a distinctive diamond-shaped lattice or braided pattern even on relatively young trunks and cut logs.
Growing Information
Origin Region
Native to the southeastern United States (Appalachian Mountains and Interior Highlands); widely naturalized across North America and Europe
Growing Season
Spring through autumn; leafs out late in mid-to-late spring, blooms with fragrant white flowers in late spring, drops leaves in early autumn
Sunlight & Water Needs
Full sun preferred; highly drought-tolerant once established; thrives in well-drained, sandy, or dry poor soils, tolerant of high alkalinity and compaction.
Mature Size
40 to 80 feet tall with a canopy spread of 20 to 35 feet; rapid growth rate (2-4 feet/year); trunk diameter up to 2-3 feet at maturity; lifespan around 60-90 years.
Special Characteristics
Extremely hard, durable, rot-resistant wood prized for fence posts and outdoor structural timber; fixes atmospheric nitrogen to enrich poor soils; excellent honey-producing species.
Wildlife & Ecology
Provides rich nectar for honeybees and wild pollinators; seeds are eaten by game birds and small mammals; foliage hosts caterpillars such as the Silver-spotted Skipper; roots fix nitrogen improving surrounding soil ecology.