Opuntia microdasys irritation so the plants must be treated with caution. The Latin specific epithet "microdasys" means “small and hairy”. The yellow flowers appear only rarely. Despite this, it is a very popular cactus in cultivation, partly because of the young plant’s comical resemblance to a rabbit’s head. It has gained the Royal Horticultural Society’s Award of Garden Merit. The very closely related "Opuntia rufida" differs in having reddish-brown glochids. It occurs further north in northern Mexico, and into western Texas. Some botanists treat the two as a single species. Opuntia microdasys Opuntia microdasys (angel's-wings, bunny ears cactus, bunny cactus or polka-dot
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