Succulent plants are the camels of the vegetable world, storing up food and water to be used not on a rainy day, but during a period of prolonged drought. This may last for a few weeks or, in extreme cases, plants have survived without rainfall for over a year. This water can be stored in either the leaves or the stems of the plants, depending on the type.
This gives rise to two distinct types of succulent plant, leaf succulents and stem succulents. The stem succulents usually have no leaves (except sometimes very small ones on young growth, soon falling off), and the green tissue of the stems takes over the work of the leaves to manufacture the food. Without leaves, the plants can reduce much of the water loss. The stems are usually very thick and full of water storage tissue, and are mostly either cylindrical or spherical in shape, sometimes being deeply ribbed. The ribs enable the plant to expand or contract as it absorbs or loses water.
Leaf succulents have plump, rounded leaves full of water storage tissue. They are often coated with wax, meal or hairs, helping to reduce water loss from their surfaces. Often these succulents have fleshy stems as well, but the leaves play the most important part in food manufacture.
The cacti, all belonging to one family, are the most popular group of succulent plants, but many other plant families have succulent members. Among the families whose succulent species are grown are the Crassulaceae, Aizoaceae, Euphorbiaceae, Asclepiadaceae, Liliaceae, and Agavaceae.
The cactus family is native to America; plants found in Europe and elsewhere have been introduced at some time in the past. There are three distinct types of plant, the pereskias, the epiphytes and the desert cacti, and theseRead more on backyardgardener.com