Glabrous, submerged, monoecious or dioecious perennial herbs with short stems, without stolons. Leaves radical, with sheathing petiole, linear, lanceolate, broadly ovate to suborbicular, cordate or reniform, basally cuneate, truncate or cordate, obtuse, actue apiculate at the apex. Flowers unisexual or bisexual, female and hermaphrodite ones solitary, sessile, staminate many, actionomorphic. Spathes tubular, bifid, elliptic or ovate, ± prominently 5-6-ribbed or 2-10-winged, wings wavy-margined, rarely spinose, pedunculate, peduncle angled. Sepals 3, linear, oblong or ovate, green, membranous margined, persistent. Petals 3, oblong, broad ovate to orbicular, much longer and wider than the sepals, basally ± fleshy, white or variously coloured. Stamens 6-15 (-20), in 3-5 whorls, filaments filiform, flattened, anthers erect, linear or oblong. Ovary included within spathe, sessile, oblong, narrowing upwards, incompletely 6- loculed by intruding parietal placenta; styles 3-15, free, each bifid; 3 stylodia present in male flowers. Fruit fleshy, oblong, attenuate at the tip, many-seeded, 6-valved, included. Seeds minute, oblong or fusiform.