Robinia pseudoacacia - Black Locust
Family: Papilionaceae

Hear the scientific name

Robinia pseudoacacia is an urban tolerant, U.S. native shade or street tree. Black Locust is known for fragrant, showy, white inflorescences in late May, quick growth in stressful situations, upright columnar habit, and often as a pioneer invader species.

F   E   A   T   U   R   E   S
  form2 form Form

-large tree

-to 50' tall x 25' wide

-upright with a single trunk that quickly yields a few major upright branches

-rapid growth rate

foliage Foliage

-dark blue-green

-deciduous

-alternate

-pinnately compound

-leaf 1-2' long, leaflets may be notched at apex

-autumn color yellowish green to green

Flowers
flowers

-white

-late May to early June

-pendulous inflorescences that are showy white and fragrant but last only a couple of weeks

-to 8" long

-tree flowering at a young age

Fruit
fruit

-green flat pods to 4" long, turning brown and persisting into early winter

Twig

-olive-brown changing to brown

-fairly slender

-zigzag

-borne with single or double prickles at some nodes

Trunk

-single-trunked with several upright branches

-light brown

-becoming lightly furrowed in youth then deeply ridged and furrowed with age

-crisscrossing ridges and brown-orange interior furrows are a trait of an old tree

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Culture

-full sun to partial shade

-very urban tolerant, especially in its adaptability to poor soils

-does not tolerate poor drainage

-rare in the trade; when available, B&B or bare root

distribution map

Hardiness

-zones 4 to 8

Origin

-native to Eastern U.S. (Appalachian and Ozark Mountains)

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Assets

-quick growth and shade under adverse conditions

-showy fragrant inflorescences in late May

-flowering at a young age

Liabilities

-prickly stems

-locust borer can be a problem to the wood and stem integrity

-poor autumn color

-short-lived

-does not flower yearly

-insect prone

Function

-native pioneer invader species

-quickly forms groves by its seeds and suckering

-good for quick growth and shade, erosion control on embankments, and reclamation of barren lands (including strip mines)

-wood is hard and rot resistant with a yellow to green interior wood; used for fence posts or any situation where rot resistance is needed

Texture

-medium in foliage and bold when bare

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Varieties and Cultivars - Search OSU PlantFacts for additional plants in this species

Alternates

-trees with showy or fragrant late spring inflorescences (Cercis canadensis, Cladrastis kentukea, etc.)

-trees with very upright growth habits (Ailanthus altissima)

-trees with rapid growth under stressful situations, especially poor soil in exposed sites (Ailanthus altissima)

 


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