Opuntia including antelopes, non-human primates, elephants, birds, and humans. When Carl Linnaeus published "Species Plantarum" in 1753 – the starting point for modern botanical nomenclature – he placed all the species of cactus known to him in one genus, "Cactus". In 1754, the Scottish botanist Philip Miller divided cacti into several genera, including "Opuntia". He distinguished the genus largely on the form of its flowers and fruits. There is considerable variation of taxonomy within "Opuntia" species, resulting in names being created for variants or subtypes within a species, and use of DNA sequencing to define and isolate various species. "Opuntia" hybridizes
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