Description
Key Characters:
Growth Form:
Annual or perennial herbs (1–)3–12(–20) dm tall, sometimes somewhat woody toward base.
Stems:
Roots:
Roots black with yellow tips.
Leaves:
Leaves compound.
Alternate.
Leaflets 3 pairs, opposite, the distal ones larger, broadly obovate to cuneate–obovate, 1.7–6.5 cm long, 1–4 cm wide.
Leaflet apices subtruncate to broadly rounded, apiculate.
Leaflet bases with 1 side rounded to cordate, the other cuneate.
Leaflet surfaces glabrous or pubescent.
Leaflet margins ciliate.
Petiolate; petiolar nectaries between the lower and occasionally the second pair of leaflets, 1–3 mm long.
Stipules linear, 3.5–17 mm long, caducous.
Flowers:
Flowers 1–2 in the leaf axils, in racemes.
Flowers caesalpinaceous. Pedicels filiform at anthesis, greatly thickened in fruit, 7–23 mm long, bracts ovate or lanceolate, 2–5 mm long, deciduous; bracteoles absent.
Calyx lobes pale green, inner ones obovate or oblong–obovate, 5.5–9.5 mm long, lobes 5, imbricate.
Corolla of 5 petals, pale yellow, the standard obcordate or cuneate–obcordate, the others oblong–ovate, the longest one 9–15 mm long.
Filaments of 4 median Stamens 1–3 mm long, those of 3 abaxial Stamens 1.5–4.5 mm long, straight, shorter than to not more than twice as long as the anthers; fertile anthers, basifixed, usually modified into sets of 4 median and abaxial anthers.
Ovary superior.
Fruit:
Pods ascending; chartaceous; linear; compressed; 4–angled; usually curved or sometimes almost straight; attenuate at both ends; 6–18 cm long; 0.2–0.6 cm wide; tardily dehiscent by both sutures; the cavity with well–developed interseminal septa.
Seeds brown and glossy; obliquely descending; compressed–rhomboid or irregular; sometimes subcylindrical in narrow fruit; 3.2–6 mm long; crackled with age; the areole 2.5–4.2 mm long.
Ploidy:
2n = 24; 26; 28
Habitat:
Elevation Range: