Bristly locust is an open branched, straggly, woody legume of vigorous growth. It attains a height of 8 to 12 feet in a few years, but normally when planted on critical sites it will grow no taller than 6 to 7 feet. It spreads rapidly on some sites by root suckers, particularly those soils light in texture. Where herbaceous plants are dense, spreading is severely restricted. Spreading by seed is secondary to root suckers. There are 23,000 seeds per pound.

Numerous small leaflets comprise the compound leaf that occurs alternately on the bristle covered branches. The sweet pea-like rose colored flowers bloom in May and June. Flowering usually begins the second year. Seed is produced in the bristle covered pods that are 2 to 5 inches in length. Seeds are about 3/16 inch in size, dark brown, and very hard.

Root suckers may appear the first year, and the thicket forming growth habit will begin by the second year. Leaf litter accumulates early, and is held in place by the many small stems that develop from the roots.