Organic Forest Plants & More

Black Locust (Robinia pseudoacacia)

Trees and Shrubs

Zones

: 4 - 8

Duration: Perennial

Growth Habit: Tree

Mature Size: Height: 80 ft. Height at 20 years: 40 ft.  Diameter: 3-4 ft.

Flowers: May - June

Fruit: September - October

Common alternate names for Black Locust: false acacia, locust-tree, yellow locust, white locust, green locust, red-flowering locust, post locust, common locust, peaflower locust.

Scientific name for Black Locust: Robinia pseudoacacia L.

Planting Information: 

Black locust is adapted to a wide variety of soil types, but grows best on sites that are deep, well drained, and derived from limestone (will not grow on sites that are permanently wet). This tree tolerates a pH range of 4.6 to 8.2. Locust also tolerates dry sites and alkaline soil.

Black locust will grow in full sun or partial shade.

Colors: Leaves: deciduous, yellow in fall. Flowers: whitish, fragrant, very showy. Fruit: brown. Bark: dark reddish brown (as the tree ages, the bark becomes thick, deeply furrowed, scaly, and dark brown).

Edible - food uses of Black Locust: N/A

CAUTION: The leaves, roots, seeds, and bark are poisionous.

Healing medicinal qualities of Black Locust: 

Cherokee used the plant as an emetic and for toothache.

Other uses for Black Locust:

Timber: The wood of black locust is strong, hard, and extremely durable (also difficult to work). It is used for fence posts, poles, ties, mine timbers, and stakes. It is also used for boxes, crates, woodenware, and novelties. Sound, straight pieces are prized for use in pole-type barns.

Landscaping: Black locust is widely planted in the United States, Europe, and Asia for erosion control, reclamation of drastically disturbed sites, due to its ease of establishment, rapid early growth and spread, and soil building abilities. It is also used for windbreaks, nurse crops, amelioration of sites, and ornamental use

Essential Oil: The essential oil from the flowers has been used as a spice, in sherberts and toilet waters.

Wildlife:

Bark of sprouts, and seedlings, are important food for cottontail rabbits in winter, especially when snow accumulates. Its seeds are rated low as wildlife food but are used to a limited extent by Northern bobwhite, other game birds, and squirrels. White-tailed deer browse the young growth.

Because older trees are usually infected with heart rot, woodpeckers often construct cavities in them. Nest cavities of the downy woodpecker, hairy woodpecker, and common flicker have been found.

General description and characteristics of Black Locust: 

Black locust (Robinia pseudoacacia), sometimes called yellow locust, grows naturally on a wide range of sites but does best on rich moist limestone soils. It has escaped cultivation and become naturalized throughout eastern North America and parts of the West.

Black locust is not a commercial timber species but is useful for many other purposes. Because it is a nitrogen fixer and has rapid juvenile growth, it is widely planted as an ornamental, for shelterbelts, and for land reclamation. It is suitable for fuelwood and pulp and provides cover for wildlife, browse for deer, and cavities for birds.

Black locust has a shallow, aggressive root system. The bark of black locust is deeply furrowed and is dark reddish-brown to black in color. It has an alternate branching pattern, which creates a zigzag effect. A pair of sharp thorns grows at each node. They are ½ to ¾ inches long, and very stout.

The pinnately compound leaves are 8 to 14 inches long, with 7 to 19 short stalked leaflets. These dull green leaflets are ovoid or oval, 1 to 2 inches long, thin, scabrous above and pale below.

The separate male and female plants have sweetly fragrant flowers that are creamy white with five petals (bean-like) arranged in a pyramidal spike. They usually bloom in May or June. Heavy seed production can be expected annually or biannually. The legume type seed is produced in a flat, brown to black pod, which is 2 to 4 inches long. There is an average of 25,500 seeds per pound. Although black locust is a good seed producer, its primary means of spread is by both rudimentary and adventitious root suckers.