A large family, nearly all natives of America and of dry or desert places, with strange characteristics, which make them easily recognized as a whole, but many of the individuals have not yet been studied or described; fleshy plants, with thick stems, often flattened, ridged or covered with knobs, mostly without leaves, usually with spines, which generally protrude from cushions of small bristles; the flowers perfect, regular, showy, and mostly single; sepals, petals, and stamens all numerous; ovary inferior, with a long style and several stigmas; fruit usually a pulpy berry, containing many seeds.

There are many kinds of Echinocactus, round or oval plants, mostly ribbed, with bunches of spines of several kinds, arranged in straight or spiral rows; the fruits scaly, though spineless.