Black Locust (also known as False Acacia)
Kingdom: Plantae, Division: Tracheophyta, Class: Magnoliopsida, Order: Fabales, Family: Fabaceae, Genus: Robinia, Species: Robinia pseudoacacia · Fabaceae (Legume, Pea, or Bean family) · Pinnately compound, deciduous
Species
Robinia pseudoacacia
Leaf Type
Pinnately compound, deciduous
Family
Fabaceae (Legume, Pea, or Bean family)
Shape
Elliptical to oval individual leaflets with rounded or slightly notched tips
Size
The entire compound leaf measures approximately 8-12 inches long, with individual leaflets around 1-2 inches long, which is typical for the species.
Margin
Entire
Arrangement
Alternate arrangement of leaflets along the rachis; alternate compound leaves on the stem
Rarity
Very Common
Color & Pattern
Dull bluish-green upper surface, paler greyish-green underneath, uniform with no striking patterns.
Venation Pattern
Pinnate venation with a prominent midrib and branching lateral veins on each leaflet
Texture & Surface
Smooth, glabrous, and matte on the upper surface with a slightly papery texture
Description
Black Locust is a medium to large deciduous tree known for its deeply furrowed, dark bark, fragrant clusters of white, pea-like spring flowers, and durable wood. The foliage consists of pinnately compound leaves that fold up at night.
Key Features
Pinnately compound leaves with oval leaflets, paired stipular spines at the nodes on young branches, and rough, rope-like furrowed bark
Habitat
Found in disturbed areas, forest edges, open woods, and along roadsides, preferring well-drained soils and full sun
Geographic Range
Native to the eastern United States, but widely naturalized across North America, Europe, and Asia
Condition Notes
The leaf appears generally healthy with a few minor yellowing spots and slight insect feeding marks, overall health grade is Good.
Interesting Facts
Black Locust wood is exceptionally rot-resistant and hard, making it a favorite for fence posts, marine pilings, and shipbuilding. It is also an important nitrogen-fixer, enriching poor soils.
Medicinal & Uses
Used extensively for heavy-duty timber, fence posts, and as an ornamental shade tree. Traditionally, various parts were used in herbal remedies, though caution is required due to toxicity.
Ecological Role
Fixes nitrogen in the soil, improving fertility for neighboring plants. Provides nesting sites and cover for birds, and flowers offer a major nectar source for honeybees.
Similar Species
Honey Locust (Gleditsia triacanthos), which has once- or twice-pinnately compound leaves and large branched thorns on the trunk, and Kentucky Coffeetree (Gymnocladus dioicus), which has much larger bipinnate leaves.
Foraging Tips
Look for trees with deeply furrowed bark and compound leaves in forest margins or waste areas. Flowers can be identified in spring by their sweet, pea-like fragrance.
Toxicity Warning
Moderately Toxic. The bark, roots, seeds, and leaves contain toxic lectins (robin) and a glycoside (robitin). Ingestion can cause nausea, weakness, and digestive upset in humans and livestock.