An annual or frutescent and persisting a few years, various in habit, erect or diffuse, simple or much branched, pilose pubescent or nearly glabrous, occasionally attaining 2 or 3 ft. or more in height. Stem terete. Leaves from 1/2–4 in. in length, the larger forms often very narrow, occasionally laterally compressed or cristate between the pairs, gland sessile shallow-saucer-shaped or flat below the lowest pair; leaflets from 10–80 pairs, linear- or oblong-falcate or nearly straight, usually with a distinct oblique mucro 1–3 (rarely 8) lines long; nervation not usually very prominent, obliquely longitudinal. Stipules finely subulate, straight, erect, from a lanceolate or ovate-lanceolate oblique base, persistent; up to 1/2 in. in length. Pedicels slender, axillary, solitary or 2 or 3 together, unequal, usually from 1/3–1 in. Buds pointed. Sepals subequal linear-lanceolate to oblong acute, and 3–4 (2–6) lines long. Petals subequal in length shortly clawed or subsessile, elliptical to rotundate, obtuse. Stamens all perfect (4–) 8–10, anthers linear much exceeding the filaments, dehiscing by terminal or shortly extended longitudinal slits. Legumes linear flattish 1 1/4–2 in. (1–3 in.) long, 1 1/2–2 1/2 lines broad. Seeds oblique-rhomboidal compressed.
