Author: (Roth) Alston
Morphological description (decapetala Caesalp compl FT16)
Liana or shrub , up to 25 m, young parts densely brown hairy, glabrescent; branchlets armed with recurved prickles (to 5 mm long) (decapetala Caes habit 428813 ). Stipules subpersistent, obliquely ovate-semicordate, 8–13 by 4–7 mm, acuminate, hairy.
Leaves: rachis 7–38 cm, hairy; pinnae 2.5–7 cm long, 3–10 pairs, hairy. Leaflets opposite, 5–12 pairs per pinna, shortly petiolulate (0.5–1 mm), membranous, elliptic-oblong, 12–22 by 4–11 mm, base rounded, apex truncate to retuse, shortly appressed hairy, rarely glabrous.
Inflorescences (decapetala Caes infl/lf 428815 ) axillary and terminal, racemose, 15–32 cm long, the rachis hairy; bracts ovate to lanceolate, 4–8 by 1–2.5 mm, pubescent; pedicels 15–30(–35) mm, pubescent, articulated 1–3 mm below the apex.
Flower buds ovoid, hairy. Hypanthium 2 mm deep and 5–10 mm wide. Sepals 6–10 by 3–4 mm. Petals 6.5–13 by 4–8 mm, clawed (claw up to 6 mm). Stamens exserted; ¾laments 10–15 mm; anthers 1.5–2 mm, glabrous. Pistil c. 17 mm long; ovary 4–5 by 1–1.5 mm, hairy or glabrous, 8–10-ovuled; style 8–9 mm, glabrous; stigma c. 0.75 mm in diameter.
Pods (decapetala Caes pods 428814 ) (pedicels 20–40 mm), oblong, 6.5–11 by 2.25–3 cm, ligneous, dehiscent, sometimes with a longitudinal wing (up to 3 mm wide), base rounded, apex rounded, beaked, often prominently veined, exocarp and endocarp easily to be separated, 4–9-seeded.
Seeds ellipsoid 8–12 by 6–8 mm, black, dull (decapetala Caes pods 428814 ).
Distribution
India, Burma, Sri Lanka, China, Japan, and Paci¾c Islands (Tahiti and Oahu, indigenous?), also cultivated in other tropical countries and then run wild. In Malesia: Sumatra (northern half), Malay Peninsula (Penang I.), Java, Philippines (Luzon), SW Celebes, Lesser Sunda Islands (Lombok, Flores, Timor).
Habitat & Ecology
Open grasslands, scrubland, forest fringes and edges of belukar on mountains between 1000 and 1700 m (up to 2000 m in Nepal), at low altitudes in some extra-Malesian regions. In Malesia also cultivated at low altitude and then run wild. Seems to prefer a dry soil.
Uses
Used as impenetrable hedges (Burkill, 1935: 397). Pods are (were?) used for tanning (See Boonkerd et al., 1991: 57).