Members of this moderately sized family of 35 genera and 1500 species are of cosmopolitan distribution, but are mostly found in southern Africa.
Most species are perennials living in dry, especially rocky, places and are xerophytic.
A number of species are found in cultivation, often as rock-garden plants, but also as house, greenhouse, and border plants. Typically, they have fleshy leaves and stems. Irritant and possibly sensitising properties have been ascribed to a few species, but little or nothing is known about the nature of the irritants. The cobalt and nickel accumulating properties of certain Crassula L. species may be of local dermatological significance. An average content of about 1400 ppm was recorded from dried plant material.