Griffiths, Bulletin of the Torrey Botanical Club 43: 523, 1916
Opuntia columbiana is referred to as O. xcolumbiana by some botanists (Anderson, 2001) who maintain that O. xcolumbiana is a hybrid between O. polyacantha erinacea and O. fragilis. Or, perhaps it is a hybrid of another O. polyacantha variety. Though it may have hybrid origins, at least some populations are stable and self-reproducing. This fact suggests that O. columbiana may be a stand-alone species and we regard it as such lacking other information. Other botanists report that O. columbiana more clearly resembles an O. fragilis hybrid over part of its range. Perhaps this taxon represents two or more phenomena that need more study. The taxon is fragile; thus the older cladodes easily break away from the main plant. Also interesting is that the shape of some cladodes (on many plants) are often narrowly obovate (about 2 x 6 inches), unlike either of the proposed ancestral species. The Flora of North America provides a description that may be correct. See the original description.