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Robinia pseudoacacia

Image of Robinia pseudoacacia

Jesse Saylor

Family

Fabaceae

Botanical Name

Robinia pseudoacacia

Plant Common Name

Black Locust

General Description

Though pretty and fast-growing, black locust is weak-wooded, short-lived and generally weedy. It is hardy, deciduous and forms a broad, upright canopy when mature. Some are more shrub-like. Natural populations are believed to have originated from the eastern United States, particularly along the Appalachians and Ozark Mountains, but have spread across much of the United States and up into Canada.

Green to blue-green compound leaves (leaves comprised of many small leaflets) cover its coarse, thorny branches through summer and turn shades of yellow and tan in fall. In spring, it produces pendulous clusters of fragrant, ivory, wisteria-like blossoms. Pink-flowered cultivars are also available. The fruits are dark brown, flattened pods filled with seeds that mature and split open by fall. Its deeply furrowed bark is variable in color and moderately attractive.

Black locust requires full to partial sun and withstands many well-drained soil types. It tolerates difficult sites, infertile soil and self-sows aggressively—factors which help explain its weedy success. The brittle branches of black locust break easily in storms and high wind and damaged trees tend to sucker. A few cultivars are less aggressive and suitable for yard and garden. This includes the compact, shrubby cultivar, 'Lace Lady.'

To learn more about the invasiveness of black locust visit the Global Invasive Species Database at: http://www.issg.org/database/species/ecology.asp?si=572.

Characteristics

  • AHS Heat Zone

    9 - 3

  • USDA Hardiness Zone

    4 - 9

  • Sunset Zone

    1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Tree

  • Sun Exposure

    Full Sun

  • Height

    30'-50' / 9.1m - 15.2m

  • Width

    20'-30' / 6.1m - 9.1m

  • Bloom Time

    Late Spring, Early Summer

  • Native To

    Northeastern United States, Mid-Atlantic United States, Southeastern United States, Central United States

Growing Conditions

  • Soil pH

    Acidic, Neutral

  • Soil Drainage

    Average

  • Soil type

    Clay, Loam, Sand

  • Tolerances

    Pollution, Drought, Salt, Soil Compaction

  • Growth Rate

    Fast

  • Water Requirements

    Drought Tolerant, Average Water

  • Habit

    Oval/Rounded

  • Seasonal Interest

    Spring, Summer, Fall, Winter

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    Light Pink, Ivory

  • Fruit Color

    Brown, Chocolate

  • Foliage Color (Spring)

    Green, Blue Green

  • Foliage Color (Summer)

    Green, Blue Green

  • Foliage Color (Fall)

    Yellow, Yellow Green, Tan

  • Bark Color

    White, Sandy Brown, Chocolate, Gray

  • Fragrant Flowers

    Yes

  • Fragrant Fruit

    No

  • Fragrant Foliage

    No

  • Bark or Stem Fragrant

    No

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    Yes

  • Edible Fruit

    No

  • Showy Foliage

    No

  • Foliage Texture

    Medium

  • Foliage Sheen

    Matte

  • Evergreen

    No

  • Showy Bark

    Yes

Special Characteristics

  • Bark Texture

    Fissured

  • Usage

    Shade Trees

  • Sharp or Has Thorns

    Yes

  • Invasive

    Yes

  • Attracts

    Birds, Butterflies

  • Self-Sowing

    Yes