Black Locust

Robinia psedoacacia

Black Locust: Full Tree - Click for larger image
  • Medium-sized tree

  • Spiny with crooked and angled trunk

  • Irregular open crown

  • Rapidly growing but short-lived

  • Height between 12-24m (40-80’)
Leaves
Twigs & Fruiting Structures
Bark
Distribution and Uses

Leaves

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Black Locust: Leaf - Click for larger image
Black Locust: Pulvini - Click for larger image

Twigs & Fruiting Structures

  • Somewhat stout, dark brown, hairless twigs; 3 bundle scars, false end buds

  • Paired thorns 6-12mm (¼-½”) next to circular leaf scars

  • Hidden white and hairy buds until large enough to come through leaf scars

  • Pea-shaped, clustered white, fragrant 5-petaled flowers appear May-June

  • Flat, narrow, dark brown pod fruit with 3-14 beanlike seeds appear September-April

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Bark

  • Light to dark grey, deeply furrowed into forking ridges, cross-hatched

Distribution & Uses

  • Prefers moist to dry sandy and rocky soils like open areas and woodlands

  • Distribution includes Pennsylvania and Ohio south to Missouri and Oklahoma; naturalized from Maine to California

  • Planted for ornamentation and erosion control on areas strip-mined for coal

  • Young shoots and bark can be poisonous to livestock, but seeds eaten by various wildlife

  • Virginia Indians used wood for bows; used today for fenceposts

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Black Locust: Bark - Click for larger image