Annual or perennial, terrestrial, epiphytic or aquatic herbs. Roots present or absent. Stem (stolons) short and delicate in terrestrial and epiphytic while usually more robust and long in aquatic species. Leaves alternate, opposite or verticillate, sometimes rosulate, entire or divided, sometimes polymorphic, covered with glandular hairs (Pinguicula) or with bladders (Utricularia). Inflorescence racemose, simple or sparingly branched or in some aquatic species supported on the water by a whorl of modified spongy leaves (floats). Flowers showy, hermaphrodite and zygomorphic. Calyx 2-5 lobed, persistent. Corolla gamopetalous, 2-lipped usually spurred or saccate. Stamens 2, attached at the base of corolla throat; filaments often winged, short, usually curved; anthers 2-celled, dorsifixed, cells diverging or confluent. Ovary superior, 1-locular; carpels 2; style usually short, persistent; stigma ± 2-lipped; ovules many, on free central or free basal placenta. Fruit a capsule, indehiscent or opens by 2-4 valves, pores or circumcissile. Seeds minute, without endosperm.