Description from Flora of China
Phaseolus marinus Burman, Index Alt. Herb. Amboin. 18. 1769.
Perennial herbs, prostrate or climbing. Stems up to several meters, glabrescent when old. Stipules 2-lobed at base, ovate, 3-5 mm; leaflets ovate-orbicular or obovate, 3.5-9.5 × 2.5-7.5 cm, very shortly setose to subglabrous on both surfaces, base broadly cuneate or narrowly rounded, apex rounded, obtuse, or emarginate. Racemes axillary, 2-4 cm; peduncles 3-13 cm. Calyx 2.5-3 mm; teeth deltoid, 1-1.5 mm, upper 2 connate. Corolla yellow; standard broadly obovate, 1.2-1.3 × ca. 1.4 cm; wings and keel ca. 1 cm. Legumes linear-oblong, 3.5-6 × 0.8-0.9 cm, pubescent when young, later glabrous, slightly constricted between seeds. Seeds 2-6, yellow-brown or red-brown, oblong, 5-7 × 4.5-5 mm; hilum oblong. Fr. Oct.
This species is edible and is used medicinally.
On sandy beaches. Hainan, Taiwan [widely distributed in tropical regions].