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Up to 25 meters tall
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Introduced from the southern United States
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A rot resistant wood with many uses
Black locust
(Robinia pseudoacacia)
Quick Identification
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Deeply grooved grey bark
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Clustered, pea-like, white flowers
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Dark brown seed pods
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Compound leaves have 7 to 21 leaflets
Impact
As a hardy species and prolific seed producer black locust spread quickly. Trees compete with native species, threatening native ecosystems. Parts of the tree are also toxic to people and horses.
Management
Cutting or girdling and removal of regrowth is effective if continued for several years. Combined cutting and herbicide treatments are most effective. Collecting and disposing of seeds will help to reduce the risk of spread.
Flower
White, pea-like flowers are about 2 cm across and grow in clusters of 10 to 25 from April to June. The flowers have a strong sweet odor and are edible.
Leaves & Stems
Compound leave have 7 to 21 oval leaflets which are a bright blue-green in colour. Young trees have smooth green or brown bark but the bark becomes grey and deeply grooved as the tree matures.
Roots
A shallow root system with nitrogen fixing bacteria make this an aggressive colonizer in disturbed soils.
Reproduction & Dispersal
Tree spreads by intentional planting and the spread of seeds. The plant can also spread through roots.
Seeds
The seeds mature in pea-like pods which can remain on the tree over winter. The seeds can remain viable for up to 10 years in favourable conditions.
Preferred Habitat
This tree thrives in disutbed areas with lots of sun and dry soils.
Interesting Facts
Though the flowers are edible other parts of the plant including stem and leaves are harmful to people and horses.
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