Herbs, shrubs, or trees; leaves opposite or alternate, palmate or pinnate, mobile at the joints (sleep-movements or some more rapid as in Biophytum); stipules present or not. Flowers perfect, regular, sepals 5, imbricate, petals 5, free or slightly connate at base, stamens 10, basally connate, sometimes only 5 fertile; ovary superior, 5-celled, styles 5, free, ovules 1 in each cell; ffuit a capsule or berry. 8 genera, 900 species; many characterized by presence of oxalic acid.