Opuntia ficus-indica (Indian Fig Opuntia) is a species of cactus and a long-domesticated crop plant important in agricultural economies throughout arid and semiarid parts of the world. Indian Fig Opuntia is grown primarily as a fruit crop, but also for the vegetable nopales and other uses. Most culinary references to the "prickly pear" are referring to this species. The name "tuna" is also used for the fruit of this cactus, and for Opuntia in general (according to Alexander von Humboldt, it was a word of Haitian origin taken into the Spanish language around 1500).
Cacti are good crops for dry areas because they efficiently convert water into biomass. Opuntia ficus-indica, as the most widespread of the long-domesticated cactuses, is as economically important as corn and tequila agave in Mexico today. Because Opuntia species hybridize easily (much like oaks), the wild origin of Opuntia ficus-indica (or even whether it has a single origin) is hard to be certain about, but Opuntia was eaten by humans at least 9000 years before the present.[1]