Opuntia macrorhiza or gravelly soils. It is one of the shorter species of the genus, rarely over 30 cm (1 foot) tall, spreading horizontally and forming large clumps. Flowers are showy and bright yellow, sometimes with red markings near the base of the petals. Fruits are narrow, red, juicy and edible. Several varieties have proposed within the species. More study is needed to determine whether these should continue to be recognized as varieties, elevated to species status, or regarded as mere synonyms. Opuntia macrorhiza Opuntia macrorhiza is a common and widespread species of cactus with the common names plains prickly pear or
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