Life cycle of the cactus. Kinds of cactuses. The importance of cactuses. There are about 2,000 species of cactuses.
Most species grow in hot, dry regions, especially in Mexico and the Southwestern United States.
But cactuses are also found in rain forests and on mountains. Some even grow in Alaska and near Antarctica. Cactuses vary widely in size and shape. For example, the giant saguaro looks like a bare tree with a thick trunk and long, upturned branches. Some small cactuses look like pincushions, starfish, or even blades of grass.