Perennial, scapigerous, aquatic
herbs, rootstocks tuberous or stoloniferous, covered with numerous root fibres.
Leaves floating or submerged, oblong, membranous. Inflorescence of spikes,
flowers bisexual on long scapes, young spike enclosed in conical sheath,
deciduous. Perianth pink, white or pale blue, 1-3, segments equal or unequal or
obsolete. Stamens 6 or more, filaments subulate, unequal, persistent, anthers didynamous. Carpels 3-6,
each with 2 or more ovules. Fruits of 3 or more follicles. Seeds erect, testa
thick or thin, embryo straight.