Cactus

Cactus, name for over 1,500 kinds of succulent prickly plant of the Cactaceae family nearly all native to America. Cacti are well adapted for desert life. They have no leaves, allowing them to conserve water. Photosynthesis takes place in the swollen stem, which may be 98% water and can swell to store the water collected by the long roots during rare desert showers. The spines that cover the stem may have 2 functions, protecting the cacti from being eaten and, where the spines form a dense mat, helping to retain moisture. The cacti produce flowers that may last for only a few hours, in some cases opening only at night. The flowers are pollinated by bees, moths, hummingbirds, and bats. Some cacti are edible. Cacti are grown for ornamental purposes and to form hedges. The peyote cactus is the natural source of the hallucinogenic drug mescaline.