HABIT : robust to sometimes gigantic arborescent evergreen herbs, stem erect, multiplying at base from hypogeal rhizomes, internodes well-developed, smooth or aculeate, ± slender to massive. LEAVES : several, borne in terminal crown. PETIOLE : sheath half as long as petiole or longer, with free apical ligule. BLADE : cordate-sagittate to sagittate, hastate to trifid, rarely trisect, posterior divisions often longer than anterior division; basal ribs well-developed, primary lateral veins pinnate, running into marginal vein, secondary laterals ± parallel-pinnate, higher order venation reticulate. INFLORESCENCE : 1(-2) in each floral sympodium. PEDUNCLE : shorter than petiole. SPATHE : erect, thick, entirely deciduous after anthesis, ± constricted between tube and blade, tube convolute, blade longer than tube, widely gaping at anthesis, ± boat-shaped. SPADIX : erect, subequal to spathe, female zone cylindric, male zone subconoid, contiguous with and much longer than female zone, fertile to apex. FLOWERS : unisexual, perigone absent. MALE FLOWER : 3-6-androus, stamens free, obpyramidal-prismatic, truncate at apex, anthers sessile, connective thick, overtopping thecae, thecae oblong-ellipsoid, dehiscing by longitudinal slit. POLLEN : inaperturate, spherical to subspheroidal, large (mean 94 µm., range 92-96 µm.), exine psilate. FEMALE FLOWER : gynoecia prismatic-cylindric, ovary 1-locular, ovules 1-2, anatropous, funicle short, placenta subbasal to basal, stylar region prismatic, thick, excavated and rugulose at apex, stigma small, on low central boss, irregular to elliptic or roundish. BERRIES : free, large, subcylindric, somewhat compressed, pericarp spongiose, at apex excavated and radiately furrowed, 1-seeded. SEED : large, obovoid to ellipsoid, testa smooth or rough, brown, embryo large, endosperm absent.
Robust to gigantic, rhizomatous helophytes forming large colonies along rivers with erect aerial stems and well-developed internodes sometimes bearing prickles; leaves borne in apical crown; leaf blade cordate-sagittate to hastate (rarely trisect), fine venation reticulate; spadix fertile to apex, male and female zones contiguous; flowers unisexual, perigone absent; stamens free; berries furrowed and excavated at apex, seeds large, brown.