SUCCULENT PLANTS are those plants remarkable for the thick and fleshy or succu lent character of their stems and leaves. This character prevails in the natural orders sactacece, mcsembryacece, and crassulacece, but frequently appears also in genera of other natural orders, as in aloes and- some other liliaeecs. It consists in a peculiar develop ment of cellular tissue. Succulent plants are remarkable for the small number of stomata (q.v.) on the green surface. They are generally found in dry climates, often as almost the only vegetation of the most arid places; although some of them occur in situ ations where moisture is often abundant; their peculiar structure, however, being appar ently intended to adapt them for enduring occasional droughts. Thus, there are not only succulent plants in the Sahara and other deserts, but in Britain, and some of them form a conspicuous feature of the flora of the mountains of Europe—as species of sedum, rhodiola rosea, etc.—where they are found in situations sometimes abounding in moisture,
but occasionally parched—on bare rocks, steep slopes with scanty soil, and the like. By the want of stomata and the store of moisture in their own cellular tissue, they are adapted for the endurance of long droughts. Yet they live in great part by nourish ment derived from the atmosphere, rather than from the soil; a fact which may easily be proved by suspending a specimen of the common yellow stonecrop (sedum acre) by means of a string, when it will be found to flourish for a considerable time, and some times to preserve its vitality as long as those planted in the ground. In dry tropical countries, succulent plants perform in part the same office which lichens and mosses do in colder regions, in preparing the first mold for future vegetation.