Herbs, annual or perennial, aquatic, rooted in mud or free-floating; roots adventitious. Stems of 2 types: vegetative and flowering. Vegetative stems short or creeping, thick. Leaves rosulate or scattered on stem, distichous; petioles mostly distinct, sometimes inflated, sheathing at base; leaf blade emersed or submerged, broadly ovate, lanceolate or broadly linear, sometimes much reduced. Flowering stem determinate, erect, usually solid, emersed bearing terminal inflorescence. Inflorescences paniculate, racemose, spicate, umbellate or 1-flowered, subtended by a spathe-like or tubular leaf sheath; bracts minute or absent. Flowers bisexual, mostly actinomorphic, sometimes zygomorphic, hypogynous. Perianth segments 6 in 2 whorls, petaloid (yellowish, blue, mauve or white), free or basally connate into a tube, tube tubular or funnelform, limb 6-lobed. Stamens usually 6, in 2 whorls, rarely 3 or 1, inserted on perianth tube, often unequal or dissimilar; filaments slender, free; anthers bithecous, long, equal or unequal, dehiscence longitudinal by slits, rarely by pores, introrse. Ovary superior, 3 or 1-locular: 3-locular with many ovules on axile placentas or 1-locular with many ovules on parietal placentas or with solitary basal ovule; style1; stigma capitate or minutely 3-lobed. Fruit 3-valved capsule or indehiscent nut. Seeds small, smooth or with longitudinal ribs or wings.

2 genera, 47 species

Pontederia crassipes