When Carl Linnaeus published Species Plantarum in 1753 – the stairtin pynt for modren botanical nomenclatur – he placed aw the species o cactus kent tae him in ane genus, Cactus. In 1754, the Scots botanist Philip Miller dividit cacti intae several genera, includin Opuntia. He distinguished the genus lairgely on the form o its flouers an fruits.[1]
Opuntia hybridizes readily atween species.[2] This can mak clessification difficult. An aa, nae aw species leetit here mey actually alang in this genus.
Opuntia macrocentra – black-spine prickly peir, purpie prickly peir, foond in southwest USA an northren Mexico
Opuntia macrorhiza – Plains prickly peir, foond throughout the Great Plains except for the northernmost areas (nae foond in North Dakota), an extendin sporadically eastward as far as Kentucky, syn. O. leptocarpa MacKensen, O. tenuispina Engelm., O. tortispina Engelm. & Bigelow; Tetraploid (2n=44)
Opuntia nichollii - Distributed throughout much o the Colorado Plateau, frae Grand Canyon north tae Price, Utah an east tae the Colorado border; Hexaploid (2n=66)
Opuntia polyacantha – Panhandle prickly peir, foond in the Great Plains, Great Basin, Mojave Desert, Colorado Plateau, an the Rocky Mountains, syn. O. rhodantha K.Schum.; Tetraploid (2n=44)
Opuntia polyacantha var. arenaria (syn. O. erinacea)
Opuntia pubescens (syn. O. pascoensis Britton & Rose)
Opuntia pusilla – creeping cactus, syn. O. drummondii Graham
Opuntia quitensis – Red Buttons opuntia (syn. O. macbridei, O. johnsonii, Platyopuntia quitensis)
Opuntia rastrera
Opuntia repens
Opuntia robusta
Opuntia rufida (sometimes included in O. microdasys)