Trichosclereids absent. HABIT : evergreen climbing herbs with woody-fibrous roots. LEAVES : numerous. PETIOLE : usually very short, entirely geniculate, concave and somewhat flattened, sheath adnate to subtended internode, rarely petiole free with long sheath (e.g. H. melinonii). BLADE : oblong, elliptic or lanceolate, ± long-cuspidate, subcoriaceous; primary lateral veins pinnate, forming a submarginal collective vein very close to margin, 1(-2) marginal veins also present, secondary laterals ± parallel to primaries, higher order venation reticulate. INFLORESCENCE : solitary, subtended by several small cataphylls, borne terminally on free, axillary branches. PEDUNCLE : very short. SPATHE : ovate-elliptic to ovate-oblong, cuspidate, convolute, opening at anthesis, then caducous. SPADIX : erect, free, stipitate, shorter than spathe, cylindric or ellipsoid. FLOWERS : bisexual, or lowermost flowers female by abortion of stamens, perigone absent. STAMENS : 4 or fewer by abortion, free, filaments short, flattened, rather broad, connective slender, thecae ovate-ellipsoid, overtopping connective a little, dehiscing by apical slit. POLLEN : zonate or dicolpate, ellipsoid-oblong or hamburger-shaped, medium-sized (mean 40 µm., range 37-42 µm.), exine foveolate or foveolate-fossulate, apertural exine psilate. GYNOECIUM : obpyramidal-prismatic, truncate, ovary 2-locular with conspicuous interseptal aperture, ovules 2 per locule, anatropous, collateral, placenta axile at base of septa, stylar region dense and thickened, broader than ovary, stigma very small, ellipsoid, oblong or subhemispheric. BERRY : shortly obovoid or obpyramidal, ± prismatic, stylar region forming a ± broad, flattened scar-like structure, 1-4 seeded, orange or greenish-white with brown apex. SEED : obovoid to ellipsoid, testa thin, smooth, black, shiny, embryo large, endosperm absent.
Climbing hemiepiphytes with distichous leaves; trichosclereids not present in any tissues; petiole usually very short, entirely geniculate and with non-annular insertion; leaf blade simple, oblong to lanceolate, primary lateral veins forming distinct submarginal collective vein, fine venation reticulate; inflorescence solitary, terminal on free axillary branches; flowers bisexual, perigone absent.