10. Mucuna macrobotrys Hance in Walpers, Ann. Bot. Syst. 2: 422. 1851.
大球油麻藤 da qiu you ma teng
Large climbing vines. Stems glabrous or with sparse reddish brown short hairs at nodes. Leaves 29-33 cm; petiole 6-13 cm, glabrous or with reddish brown short hairs; stipels slender 4-6 mm; leaflets thinly leathery or papery, glabrous or with reddish brown short hairs abaxially, lateral veins 4 or 5 pairs, uniformly strongly curved; terminal leaflet elliptic or elliptic-obovate, 11-15.5 × 3-8.5 cm, base rounded, apex with abrupt acumen ca. 1.5 cm; lateral leaflets 9-15 cm, width ratio of abaxial to adaxial halves ca. 1.7:1. Inflorescence ca. 15 cm, with 4 or 5 nodes spaced throughout length; bracts caducous; pedicels ca. 1 cm, with dark brown adpressed short hairs. Calyx with dark brown short adpressed hairs and red-brown caducous bristles; tube ca. 1 × 1.5 cm; lobes narrowly triangular, lowest ca. 10 mm and laterals ca. 7 mm, upper lip sometimes equaling lateral lobes. Corolla deep purple; standard 3.7-5 cm, with margin conspicuously pubescent in apical 1/3; wings 6-7 × 2-2.5 cm, ca. 2/3 of keel in length, apex with pubescent margin like standard; keel 7.5-9 cm. Legume asymmetric, oblong, 16-17 × ca. 4.5 cm, leathery, clothed with adpressed short hairs and sparse irritant bristles, with acute apex and persistent style, base rounded, both margins with a pair of wings 6-15 mm wide, both surfaces with 12-16 markedly obliquely transverse well-spaced parallel thinly textured lamellae up to ca. 6 mm high ± adpressed to surface and occasionally branching or interrupted, not extending onto marginal wings of fruit. Seeds 2 or 3. Fl. Dec, fr. Apr.
● Forests at low elevations. Guangdong, Guangxi, Yunnan.
Mucuna macrobotrys is distinctive in the large broad leaves with uniformly curved veins; the large purple flowers with petal margins pubescent around the apex, rather broad wing, and very long keel; and the oblong legume with acute apex, wide marginal wings, and narrowly oblique, occasionally interrupted, simple lamellae ± adpressed to the legume surface. Its apically pubescent-margined flowers are sometimes confused with those of M. macrocarpa, which differs by the bicolored corolla with usually shorter petals, the wings often relatively narrower, the standard often short relative to the keel, and the stipels rarely persistent even on very young leaves. A new species, M. hirtipetala (below), resembles large-leaved forms of M. macrobotrys in general appearance but differs by its spreading indumentum on the inflorescences, broader calyx with longer lowest tooth, and much shorter corolla without apically pubescent petals and with inner surface of the wing conspicuously long hairy.