Large herbaceous vine, climbing to ca 8 m in forest; cut parts with abundant milky sap, this drying chalklike; stems glabrous. Leaves opposite; petioles 4.5-8 (12) cm long; blades ovate to suborbicular, acuminate and downturned at apex, cordate at base, 7-15 cm long, 3.5-12 cm wide (juvenile blades to 30 cm long, 20 cm wide), glabrous, with a series of platelike glands at base above, the sides of the blade held somewhat upward. Inflorescences axillary, racemose, becoming panicles of racemes, to 35 cm long, the branches puberulent; pedicels ca 5 mm long; flowers greenish, 5-parted; calyx lobes glabrous,1.5-3 mm long; petals +/- oblong, ca 3 mm long, flexed at anthesis, the apical half with crisp white trichomes on upper surface; corona shallowly 5-lobed, the lobes ca 6 mm long; gynostegium broadened and ca 2.7 mm wide at apex; pollinia pendulous. Follicles ovate-oblong, terete, acuminate, smooth, 15-21 cm long, 7-10 cm diam; seeds bearing a coma of silky trichomes. Croat 11175. Cuba, Panama, Colombia, and perhaps southern Mexico. In Panama, known from tropical moist forest in the Canal Zone, Coclé, and Panama.