Distribution of Cactaceae:
Cactaceae consists of about 87 genera and 2,000 species. Members are distributed mainly in semi-desert and hot-desert regions of tropic and sub-tropic of America, Mexico.
Economic Importance of Cactaceae:
- Food: Fruits of Lophophora williamsii, Nopalea cochenillifera and several species of Opuntia are edible.
- Fodder: In emergency i.e. fodder famine prevails the spines of Opuntia are burnt, by scorching and then used as fodder.
- Dye: A scarlet dye – cochineal is prepared from Cochineal insects that feed upon Opuntia tuna, Napalea cochenillifera.
- Medicinal: Some species of Opuntia and Cercus have medicinal properties.
- Ornamentals: In rock gardens and unusual environment the use of Cacti – Marnmillaria, Cereus, Echinocactus, Rebutia, Opuntia etc., has become extensive.
Affinities of Cactaceae:
Cactaceae is of special interest to botanists for its combination of a primitive, unspecialized flower with highly advanced vegetative organs. To the taxonomist it presents great problems, being apparently still in a state of active evolution. As regards the position and relationship of Cactaceae, many views have been put forward. Engler retained it in the Opuntiales near the Myrtiflorae and admitted an alliance with the Aizoaceae. Bessey regarded the Cactales to be related to the Cucurbitales. Wettstein included the Cactaceae in the Centrospermae. Bentham and Hooker placed the family in the Ficoidales before the Umbellales and after the Passiflorales.