Cactus

Article By:

Strausbaugh, Perry D. Department of Botany, West Virginia University, Morgantown, West Virginia.

Core, Earl L. Department of Biology, West Virginia University, Morgantown, West Virginia.

Nobel, Park S. Department of Biology, University of California, Los Angeles, California.

Alcorn, Stanley M. Department of Plant Pathology, College of Agriculture, The University of Arizona, Tucson, Arizona.

Last reviewed:December 2019

DOI:https://doi.org/10.1036/1097-8542.101500

The common name for any member of the family Cactaceae, consisting of stem succulents that are mostly spiny with reduced leaves. There are more than 150 cactus genera with perhaps 1800–2000 species, nearly all indigenous to North America and South America. The cacti are among the most extremely drought-resistant plants and consequently they thrive in very arid regions. The group is characterized by a fleshy habit, the presence of spines and bristles and large, brightly colored, solitary flowers. There is a great variety of body shapes and patterns (Figs. 1 and 2) and many species are grown as ornamentals (Fig. 3) or oddities. A few cacti have edible fruits. The cochineal insect, which produces a valuable red dye, is cultivated chiefly on the cochineal cactus (Nopalea coccinellifera; alternatively Opuntia cochenillifera). The saguaro (Cereus giganteus; alternatively Carnegiea gigantea) [Fig. 4] of Arizona and Sonora (Northwest Mexico) is the largest of the cacti, attaining a height of 21 m (69 ft). See also: Caryophyllales; Plants, life forms of

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