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 this Opuntia is a prickly pear hybrid between O. polyacantha erinacea and O. fragilis. Some botanists report that O. columbiana more clearly resembles an O. fragilis hybrid over part of its range only. Perhaps this Opuntia represents two or more cacti that need more study. Though it may have hybrid origins, at least some populations of this prickly pear appear to be stable and self-reproducing. This fact suggests that O. columbiana may be a stand-alone Opuntia species and we regard it as such lacking other information. 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 technical description of this Opuntia. We cannot verify this description:
Shrubs, low, forming mats, 10-30 cm. Stem segments easily detached to firmly attached, green, flattened, narrowly to broadly obovate, 3.5-9 × 2.5-5 cm, low tuberculate, glabrous; areoles 4-6(-7) per diagonal row across midstem segment, oval, 3.5 × 2.5 mm; wool white. Spines in most areoles, straight, acicular, terete; major spines 0-1 per areole, reflexed to porrect (rarely ascending), gray-white to brown, (15-)25-40(-60) mm; intermediate spines 0-3, reflexed, 12-20 mm; minor spines 2-4, reflexed, yellow-gray, 3-6 mm. Glochids loosely packed, in small tuft or crescent at adaxial margin of areole, yellowish, inconspicuous, to 4 mm. Flowers: inner tepals yellow throughout, 30-45 mm; filaments white to red; anthers yellow; style white; stigma lobes green. Fruits rarely set, top-shaped to barrel-shaped, 15-20 × 15 mm, glabrous; areoles 10-15, most bearing 3-12 spines or distal spines bearing 1-3 spines. Seeds tan, large, 5-7 mm; girdle protruding 1-1.5 mm. 2n = 66.
See the original description.