See H. Jacobsen, A Handbook of Succulent Plants (3 vol., 1973).
Any plant with fleshy, thick tissues adapted to water storage. Some succulents (e.g., the cactus) store water only in the stem and have no leaves or very small leaves; others (e.g., agaves) store water mainly in the leaves. Most have deep or broad root systems and are native to either deserts or regions that have a semiarid season. In succulents, the stomata (see stoma) close during the day and open at night—the opposite of the usual pattern—in order to minimize transpiration.
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