Schery, Ann. Missouri Bot. Gard. 38:317.1951
Tendriled liana; pubescence brown-hirsute on most parts, especially branchlets, petioles, pedicels, and veins of leaf below, the trichomes ca 1 mm long; older stems flattened, irregularly twisted and folded, bearing a single wing much thicker than the major axis that bears the old stem scars. Leaves simple; stipules 5-10 mm long, foliaceous, curved, oblique, caducous; petioles 2-4 cm long (to 9 cm on juveniles), swollen at both ends; blades broadly ovate to orbicular, cleft about one-third their length when mature, cordate at base, 4-12 cm long, about as broad as long, glabrous above, bearing an apicule to ca 3 mm long at base of cleft; basal veins 11-13; juvenile leaves to 18 cm long, often cleft to base. Racemes terminal or axillary, to ca 15 cm long; flowers with 1-3 linear bracts ca 1 cm long; pedicels ca 1 cm long; calyx cup-shaped, conspicuously ca 15-ribbed, 6-8 mm long, expanding to ca 10 mm wide, the lobes slender, reflexed to spreading, ca 6 mm long and 1 mm wide; petals 5, obovate and clawed, 2-2.5 cm long, pale lavender to pink, glabrous within except at base, with dense, ± appressed brown trichomes outside ca 1 mm long, 4 of the petals spreading, ca 6 mm wide, the fifth ca 4.5 mm wide and turned sharply inward toward the lower petals, usually reflexed above the middle, the base thickened and curled inward along the margins, partly enclosing the stamens; stamens 10, unequal, the longest to 1 cm, the shortest ± equaling the length of the style; filaments thick; anthers ca 1.3 mm long, dehiscing toward the reduced petal, forming an oblique surface appressed against the reduced petal; style to ca 7 mm long, nearly surrounded by the anthers; stigma oblique; ovary elongate, coarsely pubescent. Legumes linear-oblong, flat, 8-12 cm long, 2.8-3.5 cm wide, glabrous or sparsely long-pubescent, apiculate at apex on one side, explosively dehiscent; seeds usually 5 or 6 or fewer by abortion, disk-shaped, dark brown, shiny, 0.5-2 cm diam. Croat 6152, 8126.
Occasional, along the edge of the lake. no doubt in the canopy of the forest as well. Flowers from May to September. Mature fruits have been seen from June to November and also in February.
Panama and northwestern Colombia. In Panama, known from tropical moist forest in the Canal Zone, San Blas, and Darien.