Pontederiaceae

Aquatic herbs, rooted or free-floating. Leaves spirally arranged, sheathing at base, often dimorphic: emergent leaves with a long, sometimes swollen, petiole and a spathulate, circular or ovate, cordate or hastate, lamina; submerged leaves linear. Inflorescence racemose or spicate. Bracts 0. Flowers bisexual. Perianth of 6 parts, in 2 series, united in a tube below, petaloid. Stamens (1-)3-6, dimorphic. Ovary superior, (1-)3-locular, with 1-many ovules. Fruit a capsule or nut (Pontederia).

Worldwide: 6 genera and 32 species, tropical and warm areas (especially America) with a few in the N temperate zones.