Diffusely branched, basally suffrutescent, annual or perennial herbs. Leaves opposite, simple or palmately 1-3(-7)-foliolate; stipules often spiny and acicular; leaflets entire, mucronate. Inflorescence of solitary axillary flowers. Flowers pedicellate, actinomorphic, hypogynous, pentamerous, rosy, purplish-pink or violet rarely yellow; disc minute, indistinct. Sepals 5, free, mucronate, imbricate, deciduous or persistent. Petals 5, free, clawed, imbricate, caducous. Stamens 10, free, inserted on disc, filaments filiform, unappendaged, anthers oblong. Ovary 5-carpelled, sessile, pentagonous, 5-loculed, each locule with 2, erect, collateral ovules on ascending funicle; style angular, stigma simple. Capsule deeply 5-angled, pyramidal or globular, septicidally dehiscent into 5, one-seeded cocci from the base. Seeds erect, broadly oblong, compressed with horny endosperm and mucilaginous testa; embryo straight, cotyledons ovate.