Tendriled liana, densely rufous-pubescent except sparsely so on upper surface of leaflets; stems 5-ribbed. Leaves biternate; petioles mostly 3-6.5 cm long, ribbed above; rachis margined, unwinged; leaflets +/- elliptic, blunt to acuminate, abruptly tapered to base (especially lateral leaflets), remotely serrate-dentate, the terminal leaflet mostly 7-13 cm long, 3.5-5.5 cm wide, the lateral leaflets gradually smaller. Thyrses paniculate, terminal or upper axillary, the branches to 15 cm long; pedicels to 1 cm long; flowers white, ca 7 mm long, unisexual; sepals 5, tomentulose; petals 4, oblong-obovate, ciliolate, the 2 anterior petals subtended by a rounded gland, minutely pubescent on lower margins, depressed on outer face, white in staminate flowers, purple at apex in bisexual flowers, the scales of the anterior petals to two-thirds the length of the petals, the crest yellow, thin, emarginate, the appendage villous, slender, pendent to just above glands (scales of lateral petals lacking appendages); staminate flowers with the 5 longer stamens to 6.5 mm long, the shorter ones to 4 mm long; filaments sparsely villous; style nonfunctional; pistillate flowers with the stamens 8, nonfunctional, to 3.5 mm long; ovary pubescent; style 3-4 mm long; stigmas 3, ca 1 mm long. Fruits subrectangular-oblong, ca 4 cm long, the cells rufous-pubescent, subapical, hirtellous and setose with a hornlike projection, the wings hirtellous. Croat 7823, 12714, 12715. Honduras to Panama. In Panama, known from tropical moist forest in the Canal Zone, Colón, and Darien.