When asked to describe a desert, many people imagine extreme heat and miles of sand dunes. They wonder how anything could possibly survive in such a hostile environment. Actually, this region has an incredible variety of vegetation, with the various species of cacti being some of the most recognizable.
Cacti are succulents, plants that are capable of storing water. The stem swells during wet weather, and then contracts during a drought. One of the first things people notice about desert plants are the thorns. These spines are not there just to poke. They also provide shade, break up wind currents (which reduces evaporation), and any moisture that condenses on them drips onto the ground where the roots can absorb it. There are two main types of cacti in the Southwest – opuntia and cereus. Segmented cacti, such as prickly pear and cholla, belong to the Opuntia family. Members of the Cereus family, such as saguaro, barrel, hedgehog, and pincushion, are columnar. Opuntias have fine spines, called glochids, as well as large ones; cereus cacti only have large spines.
All the cacti - saguaro, barrel, cholla, hedgehog, prickly pear, and pincushion - were used by native people for food, medicine, dyes, tools, and a variety of other uses. Click on the links for information about each of these plants.
Other desert plants, such as the agave, yucca, and sotol have an impressive array of spines, but they are not cacti. These interesting plants are actually members of the lily family.