Perennial aquatic herbs, rooting in mud or free-floating. Roots many, long and feathery in floating plants. Leaves dimorphous; the emergent ones with often swollen, long petioles, and obovate, orbicular, spathulate or lanceolate blades; submerged leaves alternate, linear, with petioles sheathing stems, shortly stipulate. Flowers in well-developed spikes or these reduced to 1 or 2 flowers. Perianth funnel-shaped, with a somewhat curved tube and 6 subequal spreading lobes, blue or mauve. Stamens 3 + 3, upper included, lower exserted; anthers dorsifixed, oblong, opening by longitudinal slits. Ovary 3-locular; ovules many; style filiform; stigma slightly dilated, entire or very shortly lobed. Capsule spindle-shaped, covered with marcescent perianth. Seeds many, small, ovoid, finely ribbed. x= 8 (aneuploids, polyploidy).
Species 7, tropical America and Africa; 1 in sthn Afr.: Eichhornia natans (P.Beauv.) Solms, N Namibia and Botswana. * E. crassipes (Mart.) Solms (Water hyacinth), originally from South America, has become one of the world's worst pests of waterways; in South Africa it is a declared weed and prohibited as an ornamental plant.