Opuntia ficus-indica 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 convert water into biomass efficiently. "O. ficus-indica", as the most widespread of the long-domesticated cactuses, is as economically important as maize and blue agave in Mexico. Because "Opuntia" species hybridize easily,
Opuntia ovaries per carpel. Placentation is parietal, and the fruit is a berry with arillate seeds. Prickly pear species can vary greatly in habit; most are shrubs, but some, such as "Opuntia echios" of the Galápagos, are trees. "O. ficus-indica" thrives in regions with mild winters having a prolonged dry spell followed by hot summers with occasional rain and relatively low humidity. A mean annual rainfall of provides good growth rates. "O. ficus-indica" proliferates in various soils ranging from sub-acid to sub-alkaline, with clay content not exceeding 15-20% and the soil well-drained. The shallow root system enables the plant to grow