perennial herbs, scapigerous, roots fibrous from tuberous rhizomes. Leaves
submerged and/or floating, mostly basal,
linear to oblong, reticulately veined with a few primary parallel veins and
many transverse secondary veins, sheathed at base. Inflorescence spike-like,
terminal, simple or 2-forked, emerging
above the water surface, spathe present but usually very early caducous.
Flowers usually bisexual, or unisexual. Perianth none or if present up to 6,
white, yellow, mauve, bluish violet. Stamens mostly 6 or more, persistent,
filaments free, anthers extrorse, 2-celled, opening by longitudinal slits. Carpels 2-4, free, ovary unilocular. Fruit a
follicle, leathery. Seeds 1-many, without endosperm.