Herbs in the warmer parts of the world, including the New World, represented in West Africa by both annuals and perennials, the latter of quite diverse habit from erect, shrub-like and a few metres high to creeping plants rooting at the nodes or with various kinds of perennating organs (stolons in Pollia, rhizomes in Palisota spp., bulbs or tuberous roots in Cyanotis).

Members of the family may be recognised by their jointed stems bearing entire juicy leaves with convergent (parallel) venation, the blade arising from a closed sheathing base (sometimes with an intervening false petiole), its margins supervolute or involute when young. The flowers are small, threepart, delicate and short lived, in compound cymes, which are often subtended by spathe-like bracts. The fruit is generally a loculicidal capsule, and the seed always has an embryostega or operculum, a patch of testa (opposite the hilum), which is pushed off during germination.

Two species introduced from America are commonly grown in gardens. These are Rhoeo spathacea, with a rosette of purple and green sword-shaped leaves and white flowers, and Zebrina pendula, a trailing herb with purplestriped leaves and pink and white flowers.

Three genera are unusual in that the closed tubular sheath of the bract subtending the inflorescence is penetrated by the axillary inflorescence, which emerges through a hole. The genera concerned are Buforrestia, Coleotrype and Forrestia. Commelina is the only genus with leaf-opposed inflorescences, the remaining genera having the more common kind of terminal inflorescence.