Stem firmly herbaceous or woody below, annual or of 2–3 years' duration (Dr. Welwitsch), erect, often forming dense bushy masses, a few feet in height, glabrous or nearly so. Leaflets membranous, in 4–5 pairs, ovate- or elliptic-lanceolate, usually acute or acuminate, glabrous minutely ciliolate or obsoletely pubescent beneath, 1 1/2–2 1/2 in. long, the upper varying to 3–4 in.; common petiole without interpetiolular glands, but with a short obtuse gland near the base, black when dry. Stipules lanceolate or ovate-lanceolate, membranous, deciduous. Flowers in short few-flowered axillary racemes or fascicles, the peduncle and pedicels seldom exceeding 1 in., or towards the ends of the branches the fascicles confluent forming an interrupted terminal raceme; the leaves reduced or bract-like. Bracts thin, linear-lanceolate or oblong acuminate, deciduous. Sepals obtuse, glabrous or nearly so, the outer rather shorter. Petals obtuse, venose. Two anterior stamens larger, with slightly curved anthers 1/4 in. long, shortly and broadly produced at the apex. Legume 2-valved, linear compressed, slightly falcate or straight, apiculate, rather coriaceous, margined with straight sutures; 3 1/2–5 in. long, 3–4 lines broad; the pericarp when dry usually depressed between the seeds, which are usually but not always flattened in the same plane as the pod. Cotyledons plane or nearly so, in the larger diameter of the seeds, enclosed between thick layers of albumen.
