Herbs, rarely shrubs. Leaves opposite or alternate, simple and entire, exstipulate. Flowers hermaphrodite or unisexual, usually regular, generally arranged in spikes or cymes or clusters, each flower seated within 2 scarious bracteoles and subtended by a larger scarious bract. Perianth inferior, persistent, rigid and scarious, often coloured, of 4–5 free or slightly connate segments, imbricate in bud. Stamens hypogynous, 4–5, seldom fewer, opposite to the sepals; filaments free or connate, or united with intervening staminodia into a cup-shaped ring; anthers 1- or 2-celled. Ovary superior, 1-celled; style long or short, simple or divided into 2–3 branches or separate styles; ovules 1 or more, attached to a slender basal funicle. Fruit usually a membranous utricle, rarely a capsule or berry, enclosed or resting upon the persistent perianth. Seeds 1 or more, usually compressed, vertical; albumen farinaceous; embryo annular or curved.

A moderate order, comprising 48 genera and nearly 500 speeies, most plentiful in tropical or warm countries, absent in cold climates or on the tops of high mountains. Some species of Amarantus and Celosia (cockscomb) are often cultivated in gardens, but as a whole the order is composed of weedy unattractive plants possessing no useful properties. The only New Zealand genus is found in all warm countries.