Perennial aquatic or marsh herbs, with basal or alternate entire crenate or 3-foliolate leaves, and clustered regular perfect flowers. Calyx inferior, deeply 5-parted, persistent. Corolla funnel form to rotate, 5-lobed or 5-cleft, the lobes induplicate-valvate, at least in the bud. Stamens 5, borne on the corolla, and alternate with its lobes; filaments mostly short; anther-sacs longitudinally dehiscent; pollen-grains 3-angled. Ovary 1-celled,the 2 placentae sometimes intruded; style long, short or none. Fruit a capsule, or indehiscent.

Five genera and about 35 species, widely distributed.

Leaves 3-foliolate; swamp plant.

1. Menyanthes.

Leaves simple, entire, cordate, floating.

2. Nymphoidcs.