Genus of about 130 species of annual, biennial, and perennial succulents, shrubs, climbers and small trees, occurring in semi-desert or shady areas of Saudi Arabia, Yemen, C. Africa, South Africa, Madagascar, Asia, Australia, and tropical America. Some are tree like or shrubby, others are more spreading in habit. All have fleshy stems bearing simple to 2 pinnatisect, rarely pinnate, toothed or scalloped, fleshy leaves, arranged in opposite pairs.
