Benth., Comm. Leg. Gen. 55.1837
Slender vine. Leaves trifoliolate; stipules ovate, ca 2 mm long; petioles 1.5-4 cm long; petiolules to 15 mm long on terminal leaflet, ca 2 mm long on lateral leaflets; leaflets lanceolate to oblong, acute to acuminate, rounded at base, villous above, velutinous below, the terminal leaflet 5-13 cm long, 2.5-5.5 cm wide, the lateral leaflets somewhat reduced, the veins prominent on both surfaces. Racemes axillary; peduncles 8-11 cm long; rachises to 2 cm long; bracts ovate, acute, striate, to 8 mm long, caducous; calyx bifid, shallowly lobed, ca 10 mm long, pubescent, becoming glabrate in age except for carinal lobe, the carinal lobe arcuate, slender, ca 5 mm long; standard ± rounded to emarginate, to 3.5 cm long and 4 cm wide, sparsely pubescent and usually white outside, blue to orchid or violet-purple inside, prominently marked with purple and white along median line, often yellow at base, clawed at base; keel and wings white or tipped with violet, ca 3 cm long, the keel at first weakly sealed on both sides except at base; stamens 10, diadelphous, enclosed within keel, the staminal column forming an arched open tube below, fan-shaped at apex; style to ca 3.5 cm long, held within the open staminal tube, flat, truncate and puberulent at apex, longer than anthers, the outer margin bristled. Legumes 10-14 cm long, ca 7 mm wide, long-acuminate at apex, sparsely appressed-pubescent, the lateral margins raised; seeds as many as 25, black, round, flattened, ca 3 mm diam. Croat 4398, 6986.
An occasional weed in clearings. Flowers and fruits throughout most of the year, especially in the dry season, but principally in December and January.
The style extends from the keel beyond the anthers and presses against the wing and keel petals. Both of its flat surfaces are covered with a thick, pasty layer of pollen.
Standley (1933) also reported Centrosema virginianum (L.) Benth., but that species does not appear to be distinct from C. pubescens Benth. in Panama. It is reported to range from Mexico to Panama, but possibly does not come as far south as Panama.
Mexico to tropical South America; West Indies; introduced in the Old World tropics. In Panama, known principally from tropical moist forest in the Canal Zone, Bocas del Toro, San Blas, Chiriqui, Veraguas, Los Santos, Herrera, Panama, and Darien; known also from premontane dry forest in Herrera, from tropical dry forest in Coclé and Panama, from premontane wet forest in the Canal Zone, Coclé and Panama, and from tropical wet forest in Darien.