Opuntia echios Opuntia echios Opuntia echios is a species of plant in the Cactaceae family. It is endemic to the Galápagos Islands (Ecuador) and is commonly known as the Galápagos prickly pear, but there are five other species of prickly pears that also are endemic to the archipelago ("O. galapageia", "O. helleri", "O. insularis", "O. megasperma" and "O. saxicola"). There are five varieties of "Opuntia echios", each with a different appearance and distribution: "Opuntia echios" var. "echios" on the islands of Santa Cruz, Baltra, Daphne Major and South Plaza, "Opuntia echios" var. "barringtonensis" on Santa Fe, "Opuntia echios" var. "gigantea" near Academy
Opuntia readily between species. This can make classification difficult, yielding a reticulate phylogeny where different species come together in hybridization. Also, not all species listed here may actually belong in this genus, meaning that "Opuntia" is not a monophyletic group. "Opuntia" also has a tendency for polyploidy. The ancestral diploid state was 2n=22, but many species are hexaploid (6n = 66) or octaploid (8n = 88). Chollas, now recognized to belong to the distinct genus "Cylindropuntia", are distinguished by having cylindrical, rather than flattened, stem segments with large barbed spines. The stem joints of several species, notably the jumping cholla ("Cylindropuntia