|Abstract||Perennial lactiferous freshwater herbs, rhizome short tuberous with fibrous roots. Leaves radical, submerged or floating, base sheathing, oblong to linear, entire or crisped, often long-petiolate; nerves lengthwise parallel, connected by numerous oblique transverse veins. Spike emerging from the water, simple or 2-8-forked, without bracts, subtended by a mostly caducous basal sheath (spathe). Flowers bisexual (rarely by abortion unisexual), small, spicate-scapose, white, rose, purple, yellow or yellowish-green. Perianth segments 2 (1-3, or absent), equal or unequal, usually persistent. Stamens in 2 rows, 6 (or more), free, hypogynous, persistent; filament filiform; anthers extrorse, small, 2-celled. Pollen subglobose or ellipsoid. Gynaecium superior, apocarpous; carpels 3-6, sessile, each with a simple style. Ovules 1-8 (or more), anatropous. Mature carpels inflated, opening along the back. Seeds without endosperm; outer testa often loose; embryo straight, elongate.|
Distr. About 40 spp. described, Africa, Madagascar, Ceylon, SE. Asia, through Malaysia (very rare) to N. Australia, centering in Africa and Madagascar.