Annual or perennial often tufted herbs. Leaves opposite or alternate, simple; stipules scarious (wanting in Scleranthus). Flowers usually hermaphrodite, regular, inconspicuous. Perianth (calyx) inferior, herbaceous or coriaceous, persistent and often hardened in fruit; lobes 4–5, imbricate. Petals usually wanting. Stamens hypogynous or perigynous, as many as the perianth-lobes and opposite to them or fewer by abortion, sometimes a single one only; filaments short, subulate; anthers small, didymous. Ovary superior, ovoid, 1-celled; style terminal, 2–3-fid; ovule solitary, erect or pendulous from a basal funicle. Fruit a utricle enclosed in the persistent perianth. Seed with farinaceous albumen; embryo usually annular.

A small order, found in most parts of the world, mainly composed of weedy inconspicuous plants of no economic value. Genera 17; species about 90. The New Zealand genus is found in the temperate regions of both hemispheres.