Black Locust
Black locust (*Robinia pseudoacacia*) is a deciduous tree in the pea family (Fabaceae) native to parts of the eastern and south-central United States.
Black locust (*Robinia pseudoacacia*) is a deciduous tree in the pea family (Fabaceae) native to parts of the eastern and south-central United States. It is widely planted and naturalized outside its native range, and is known for its fragrant white flowers, nitrogen-fixing ability, and very durable wood.
Description
Black locust is a medium-sized deciduous tree, typically reaching about 18–30 m (60–100 ft) in height. It is characterized by pinnate leaves, fragrant white flower clusters, and flat seed pods. The tree has furrowed bark and sharp spines on young shoots. All parts of the plant are reported as poisonous if ingested.
Distribution and habitat
The species is native to parts of the eastern and south-central United States, with its native range extending from the Appalachians westward into Arkansas and Oklahoma. It has been widely introduced and naturalized in Europe, southern Africa, Asia, and parts of Canada, including Ontario to Nova Scotia and British Columbia. Black locust grows well in disturbed areas, roadsides, and other open sites.
Ecology and uses
Black locust is a nitrogen-fixing legume that improves poor soils and is often used in reclamation and erosion control. Its wood is highly valued for durability and decay resistance, making it suitable for fence posts and other applications where rot resistance matters. The tree also produces fragrant flowers that attract pollinators.
Invasiveness and management
Outside its native range, black locust can spread aggressively by seed and underground stems. In some regions it is considered invasive because it can form dense stands and displace native plants. Management efforts may be required to control its spread.
Key facts
- Black locust belongs to the legume family and is scientifically named *Robinia pseudoacacia*.
- It is native to parts of the United States, from the Appalachians westward into Arkansas and Oklahoma.
- The species has been widely introduced and naturalized in North America and other regions, including Canada.
- Black locust fixes nitrogen and is often used in reclamation and erosion control.
- All parts of the plant are reported as poisonous if ingested.
Black locust occurs in parts of Canada, including Ontario to Nova Scotia and British Columbia, and is recognized in Canadian horticulture and forestry contexts as a naturalized and sometimes invasive species.
Frequently asked questions
What is black locust?
Where is black locust native?
Why is black locust planted so widely?
Is black locust invasive?
Is black locust poisonous?
References
- U.S. Forest Service — https://www.fs.usda.gov/wildflowers/plant-of-the-week/Robinia-pseudoacacia.shtmlSupports: Native range, Canadian occurrence, and introduction history
- USDA Natural Resources Conservation Service — https://www.nrcs.usda.gov/sites/default/files/2022-09/BlackLocust.pdfSupports: Native range, growth form, spread, and toxicity
- Native Plant Trust — https://gobotany.nativeplanttrust.org/species/robinia/pseudoacacia/Supports: Identification, habitat, nitrogen fixation, and invasiveness
- NC State Extension Plant Toolbox — https://plants.ces.ncsu.edu/plants/robinia-pseudoacacia/Supports: Size, family, life span, and invasive tendency
- Ohio State University Extension — https://www.ohioweedguide.org/singlerecord.asp?id=65Supports: Habitat, spread, invasiveness, and toxicity
- George Mason University — https://perec.science.gmu.edu/native-plants/black-locust/Supports: Scientific name and common name