Annual or perennial herbs, sometimes woody at the base or, rarely, small shrubs (Psilotrichum scleranthum). Stipules 0. Leaves simple, alternate or opposite. Inflorescence various, bracteate; bracts hyaline to membranous, straw-coloured to white, subtending one or more flowers. Flowers bisexual or unisexual, mostly actinomorphic with 2 bracteoles, frequently in ultimate small 3-flowered cymes, the lateral flowers often sterile and modified into scales, spines, hooks or hairs. Tepals often green or white or variously coloured, usually 5, arranged in 1 whorl, membranous to firm, finally hardening and often falling with the ripe fruit. Ovary superior, 1-locular. Fruit a capsule, rarely a berry.