HABIT : climbing herbs, stems rather woody, lower branches rooting, upper ones free and hanging, nodes rarely bearing short, clustered spines (P. armatus), buds of lateral shoots sometimes perforating the leaf sheath or ± infra-axillary. LEAVES : distichous, juvenile plants of some species of shingle form (petiole very short, blades broad, appressed, partially overlapping). PETIOLE : geniculate (articulate) apically, either broad, completely flattened and usually auriculate apically, or morphology normal with a long sheath, sometimes sheath reduced to a pair of hyaline ridges (series Goniurus). BLADE linear-lanceolate to ovate or elliptic, sometimes oblique; primary lateral veins either mostly arising near base of blade, long arcuate, and running into marginal vein near apex, or primary lateral veins pinnate, weakly differentiated, forming submarginal collective vein, 1-2 marginal veins also present, higher order venation reticulate in all types. INFLORESCENCE : axillary or infra-axillary, solitary or forming short branching systems of several inflorescences, bearing 4-6 (sometimes more, e.g. P. insignis) rigid, coriaceous cataphylls at the base, often bearing the spathe near the middle of peduncular axis. PEDUNCLE : short to long, sometimes reflexed. SPATHE : ovate to linear, rarely very long (P. mirabilis). SPADIX : globose, ovoid, cylindric, ellipsoid or obovoid, sessile to long-stipitate, densely or laxly flowered. FLOWERS : bisexual, perigoniate; tepals 4-6, usually fornicate, free or partially to completely connate (e.g. P. rumphii). STAMENS : 4-6, filaments oblong, flattened, connective slender, thecae ellipsoid, dehiscing by slit. POLLEN : monosulcate, ellipsoid-oblong, small (mean 21 µm., range 16-25 µm.), exine foveolate to reticulate or subrugulate, muri psilate or minutely tuberculate. GYNOECIUM : ovary ovoid-oblong or depressed, (2?-)3-locular; ovules 1 per locule, anatropous, funicle short, placenta axile at base of septum, stylar region sometimes as broad as ovary, stigma discoid-hemispheric to umbonate. BERRY : ellipsoid to ovoid, 1-3-seeded, red. SEED : ellipsoid, testa smooth, embryo large, endosperm absent.