succulent (sŭkˈyələnt) [key], any fleshy plant that belongs to one of many diverse families, among them species of cactus, aloe, stonecrop, houseleek, agave, and yucca. Most succulents are indigenous to arid or semiarid regions, and their succulence is simply an evolutionary adaptation to the extreme heat and dryness of the environment. Typically the plants have greatly reduced leaves with a hard and heavily cutinized outer surface which minimizes evaporation from the inner, juicy tissue that can retain and store water over long periods. Many are grown horticulturally for their interesting and often grotesque forms, e.g., the ice plant; a few have very attractive flowers.
See H. Jacobsen, A Handbook of Succulent Plants (3 vol., 1973).