Annual or perennial herbs, sometimes subshrubs, often forming mats. Lvs usually alternate, rarely opposite or verticillate, simple, entire or toothed, usually spaced along stem, sometimes crowded in terminal rosettes, occasionally scale-like. Infl. a terminal or axillary, corymbose, helicoid or secund cyme (often several cymes terminating a main inflorescence stem), sometimes paniculate, usually many-flowered. Fls 4-5-(9)-merous, erect to horizontal. Sepals free or almost so, equal or unequal. Petals free or slightly connate at base, erect or patent with corolla often star-like, white, yellow, greenish, pink to purple, very rarely blue, thin and scarcely succulent. Stamens usually twice as many as petals and in 2 equal whorls, occasionally as many as petals and in 1 whorl, free or occasionally epipetalous, exserted. Scales free, very variable in shape and size. Carpels free or almost so, usually 4-5. Seeds usually numerous, sometimes 1-few.