Fig opuntia is grown primarily as a fruit crop, and 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 Taino origin taken into the Spanish language around 1500.
Cacti are good crops for dry areas because they efficiently convert water into biomass. O. ficus-indica, as the most widespread of the long-domesticated cactuses, is as economically important as maize and blue agave in Mexico today. Because Opuntia species hybridize easily (much like oaks), the wild origin of O. ficus-indica is likely to have been in Mexico due to the fact that its close genetic relatives are found in central Mexico.