Vigna oblongifolia A.Rich.

Annual, more rarely perennial, prostrate or climbing herb, rarely suberect, usually 0·9–4·8 m. long from a somewhat woody rootstock.. Stems slender, covered with adpressed spreading or reflexed ± bristly hairs.. Leaflets 3, ovate to linear-lanceolate, 1·5–12 cm. long, 0·2–2·5(–3·5) cm. wide, rounded to acute and mucronulate at the apex, cuneate or rounded at the base, rather sparsely adpressed pubescent on both surfaces; petiole 1·5–6·5 cm. long; rhachis 0·5–1·5 cm. long; petiolules 1–3 mm. long; stipules ovate-lanceolate, 2–3 mm. long, cordate and slightly prolonged below the point of insertion.. Inflorescence dense, 2–10-flowered; rhachis 0·5–2·5 cm. long, somewhat zigzag and with tumid glands at the pedicel-bases; peduncle 2–35 cm. long, often very hairy at the apex and pilose below; pedicels 2–5 mm. long; bracts deciduous, ovate-lanceolate, 1–1·5(–3) mm. long; bracteoles subpersistent, lanceolate, 1·5–2·5(–5) mm. long.. Calyx pubescent; tube 1·5–2 mm. long; lobes triangular-lanceolate, 1–4 mm. long, the lowest narrow, the upper pair joined to form an apiculate lip.. Standard yellow or greenish-yellow, green or sometimes purple-flushed outside, obovate, 6–10 (–11) mm. long and wide, emarginate or truncate, glabrous; wings pale or bright yellow; keel pale yellow or greenish-white, green at the tip with the beak short, not incurved.. Pods ± deflexed, linear-cylindrical, compressed, 3–9-seeded, 2·3–6·5 cm. long, 3–5 mm. wide, curved or almost straight, slightly constricted between the seeds, covered with adpressed, usually mixed pale ferruginous and white bristly hairs.. Seeds greenish, brown or dark reddish-brown often mottled with black, irregularly oblong, ovoid or subglobose, sometimes angled on margin opposite the hilum, longest dimension 2–4·5 mm., shorter dimension 2–3·2 mm., 1·5–2·2 mm. thick; aril eccentric, shaped like a fork with a short central prong.

It is a tropical plant. It grows in hot arid places with a marked dry season. The dry season can be 6-11 months. It can be in dry sandy soil. It grows between 335-1,300 m above sea level. It often grows along the edges of swamps. It can grow in arid places.