The Cactaceae or cactus family is one of the more recognizable plant families, although the African euphorbias are often mistaken for cacti. The Cactaceae is restricted to the New World with a single exception, Rhipsalis baccifera, which grows in Africa, Madagascar and Sri Lanka, however it's possible that that species originated in the New World since it exists there as well. Cacti are residents of deserts and semi-deserts, and the family contains about 2000 species in about 100 genera. They are succulent plants adapted to extremely hot and dry environments, their stems containing the chlorophyll they need to produce food, and the leaves having evolved into spines for protection from predators. The flowers are generally large and radially symmetrical. Cacti are a relatively recently evolved family since the continents moved apart, and many have important commercial uses.