Lianas, the branchlets terete, without interpetiolar glandular fields or pseudostipules. Leaves 3-foliolate, or 2-foliolate with a trifid tendril or tendril scar. Inflorescence a terminal raceme. Calyx short-cupular, truncate, minutely 5-denticulate; corolla magenta, tubular-funnel-shaped, the tube mostly glabrous, lightly lepidote toward apex. Thecae glabrous, straight, divaricate. Ovary oblong, densely lepidote; ovules 4-seriate in each locule; disk pulvinate. Fruit unknown.
Endemic to the Guayana Shield in Colombia, Venezuela, Guyana, Suriname, and Brazil; 1 species.
Potamoganos microcalyx (G. Mey.) Sandwith, Recueil Trav. Bot. Néerl. 34: 221. 1937. -Bignonia microcalyx G. Mey., Prim. Fl. Esseq. 211. 1818.
Liana. Nonflooded evergreen lowland forests, 100-400 m; Amazonas (Cerro Huachamacari to Río Cunucunuma, 23 km north of Puerto Ayacucho, Río Cuao, Río Orinoco below San Fernando de Atabapo, San Carlos de Río Negro). Colombia (Amazonas), Guyana, Suriname, Brazil (Amazonas, Roraima). Fig. 407.
The leaves of this species are quite similar to those of Ceratophytum or Distictella, but the flowers and inflorescence are more like those of Mansoa or Roentgenia.