BLACK LOCUST | Robinia pseudoacacia

(common locust, yellow locust, false acacia, treenail)


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description: deciduous tree

place of origin: eastern North America

urban habitat: a fast growing tree that tolerates a wide variety of soils, from saline roadsides to acid mine tailings and on dry sandy sites in full sun; found in minimally maintained parks, vacant lots, waste dumps, emergent woodlands, highway banks. “Nitrogen-fixing” root nodules containing symbiotic Rhizobium bacteria allow black locust to generate its own fertilizer on low-nutrient sites.

ecological function: heat reduction in paved areas; tolerant of roadway salt and compacted spoil; soil improvement; erosion control on slopes; food and habitat for wildlife.

history: Robinia pseudoacacia has been widely cultivated since the 1700’s as an ornamental and a source of rot-resistant wood for fence posts. In its native Appalachia, Black locust was used as a support in coalmines. It was one of first American trees planted on degraded soils in Europe and has now become naturalized there. Black locust is widely planted today on waste reclamation sites including landfills and mine tailings. The flowers of Robinia pseudoacacia are said to contain useful agents, acting as antispasmodic, antitumor, diuretic, laxative, emollient and are used as an aromatic compound in perfumery. The cooked flowers have been used in making jams and beverages and its cooked seeds consumed like peas. Native Americans used the root bark to induce vomiting. Other parts of the tree are considered toxic to humans. The tree has other potential practical uses: a yellow dye can be obtained from its bark and its trunk yields a hard, close-grained wood useful for making fence posts, treenails and floors.