Small, more or less aquatic annuals or rarely perennials. Leaves opposite, simple, entire, more or less petiolate, with stipules. Flowers minute, solitary in leaf axils, bisexual, hypogynous, actinomorphic. Sepals 3–4, membranous, free or united at base. Petals 3–4, free. Stamens 6 or 8. Styles 3 or 4, very short; stigmas capitate. Ovary 3- to 4-celled, each with numerous ovules on axile placentation. Fruit a 3- to 4-celled capsule.

Contains 2 genera and about 40 species; cosmopolitan.

Elatine L.

Annual or perennial herbs in wet places. Leaves opposite, simple, entire, with stipules. Flowers minute, solitary in leaf axils or in cymes, bisexual, hypogynous, actinomorphic. Sepals 3–4. Petals 3–4, reddish or pinkish-white. Stamens 6 or 8. Styles 3 or 4; stigmas capitate. Fruit a 3- to 4-celled capsule.