A Cactus (pl., cacti or cactuses) is a type of usually succulent plant belonging to the flowering plant family, Cactaceae. Cacti are well-known natives of the desert areas in the Americas. They have also become naturalized to similar environments in other areas of the world.
Like other succulents, cacti are well-adapted to life with little precipitation. Their leaves have evolved into needles or spines, which in addition to allowing less water to evaporate than regular leaves, defend the cactus against water-seeking animals. Their photosynthesis is carried out by the enlarged stems, which also store water. Unlike many other succulents, the stem is the only part of a true cactus where this takes place. Very few members of the family have leaves, and when present these are rudimentary and typically awl-shaped.
Cacti come in many varieties in a wide range of shapes and sizes. The Cactaceae (depending upon the authority) has between 24 and 220 genera (90 is perhaps a good number) with anywhere from 1,500 to 1,800 species. Some grow to great heights. Some cactuses produce beautiful flowers, which like spines and branches arise from areoles. Many cactus species are night-blooming, as they are pollinated by nocturnalinsects or small animals, principally moths and bats.
A number of cactus species are cultivated for use as houseplants, as well as for ornamental gardens. They often form part of xerophilic (dry) gardens in arid regions. Some cacti bear edible fruit.
