herbs, erect. Leaves floating or emerged, lanceolate or sagittate, floating
ones mostly cordate, submerged ones
linear, emerged ones sagittate, entire, obtuse to acuminate. Inflorescence a
raceme, often a panicle. Flowers in whorls of 1-14, mostly 3. Unisexual or bisexual
with upper ones male and lower ones female. Sepals 3, herbaceous, patent or
reflexed. Petals 3, deciduous, white or rarely pink. Stamens 7-many, filaments
compressed. Carpels many, crowded on a large receptacle, laterally flattened.
Fruit an achene, globose or oblong. Seed horse-shoe shaped.