Black locust
Robinia pseudoacacia
Washington State Classification
Class C — Widespread, County-Selected Control
While being a desired shade tree in parts of Washington where it can be difficult to grow trees, black locust also invades other habitats, changing grassland habitats into monoculture forests.
Quick Reference
Identification
Growth Habit
This fast growing, hardwood deciduous tree can reach 40-100 feet, and can live for up to 100 years.
Leaves
The light green leaves are divided into 9 to 19 oval-shaped leaflets.
Flowers
Flowers grow in large, drooping, flower clusters that can be up to 10 inches long. Each individual flower in this cluster is white or cream colored, and is a typical pea-family shaped flower: a keel-shape of 2 petals at the bottom, two vaguely spoon-shaped petals on top of the keel, and petal forming a "banner" at the top.
Fruit & Seeds
A flattened peapod which will start green-red and ripen to brown as it hardens with 2 to 15 flattened seeds inside.
Impact
While being a desired shade tree in parts of Washington where it can be difficult to grow trees, black locust also invades other habitats, changing grassland habitats into monoculture forests.
Ecology & Spread
Habitat
Grows well in open and sunny areas, such as grasslands, shrublands, pasture, disturbed sites, and roadsides. Is drought tolerant, and can grow in dry uplands as well as wetland and riparian areas.
Spread Mechanisms
Reproduction
Seed and extensive root suckering.
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