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A large family of dicotyledonous xerophytic plants, the cacti. It includes over 2000 species in about 87 genera; some authorities however recognize many more, over 300 genera being listed in some classifications. The cacti are limited in distribution to the drier regions of South and Central America and central and southern North America. Some have become naturalized elsewhere, e.g. prickly pears (Opuntia) in Australia and the Mediterranean, and Rhipsalis, which is probably naturalized rather than native, in southern Africa. Cacti are succulents and, being leafless (the leaves are reduced to spines), are a particularly distinctive group of plants. It is this that has led to their popularity as unusual pot plants. Photosynthesis is carried out by the green expanded stems, which show various advanced characteristics in the arrangement of vascular tissues and many other features. The flowers however, which are borne singly directly on the stem, are comparatively primitive having large numbers of stamens, petals, sepals, and bracts arranged spirally. The fruit is a berry.
Very few cacti are of use to man, except as ornamentals, though prickly pears are grown for their fruits in California, Mexico, and some Mediterranean countries.
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