Lianas, the branchlets acutely hexagonal with detachable ribs, without interpetiolar glandular fields; pseudostipules spathulate, early caducous. Leaves 2- or 3-foliolate; terminal leaflet often replaced by a basically 3(-15)-fid tendril, the apices usually dividing several times and often with thickened disks. Inflorescence a terminal raceme or racemose panicle. Calyx cupular, truncate, thick, ± minutely 5-denticulate, lepidote and puberulous; corolla white, relatively thick, tubular-campanulate, densely pubescent outside. Anthers glabrous, the thecae straight, divaricate. Ovary ellipsoid-cylindric, contracted above the disk, densely simple-puberulous with adpressed trichomes; ovules multiseriate in each locule; disk annular-pulvinate. Fruit a woody capsule, elliptic, ± flattened, the valves parallel to septum, densely spiny. Seeds thin, winged, the body surrounded by the clearly demarcated hyaline-membranous wing.
Mexico to Brazil and Argentina; 3 species, 1 in Venezuela.
Pithecoctenium crucigerum (L.) A.H. Gentry, Taxon 24: 123. 1975. -Bignonia crucigera L., Sp. Pl. 623. 1753.
Bignonia echinatum Jacq., Enum. Syst. Pl. 25. 1760. -Pithecoctenium echinatum (Jacq.) Baill., Hist. Pl. 10: 8. 1888.
Bignonia tiliaefolia H.B.K., Nov. Gen. Sp. (quarto ed.) 3: 136. 1818 .
Liana. Semideciduous to evergreen lowland or lower montane forests, 100-800 m; Bolívar (near Cerro Paují), Amazonas (San Juan de Manapiare). Common and widespread elsewhere in Venezuela; Mexico to northern Argentina and Uruguay. Fig. 401.
The spiny "peine de mono" fruit is unmistakable (more elliptic and much more densely spiny than Clytostoma); vegetatively it is similar to Amphilophium but differs in the much-divided tendrils, spathulate pseudostipules, and uniformly simple trichomes.