Editing Eastern Prickly Pear (section)

=== Highly Variable Morphology ===

''Opuntia humifusa'' exhibits a particularly variable phenotype and, for this reason, it has been given several different scientific names across its rather broad range in the Eastern United States and Canada.  Over the years, several botanists found specimens of ''O. humifusa'' which, in one way or another, differed in appearance so drastically from those with which they were familiar that it seemed quite obvious that the new find must represent a different species.  Today, most of these erroneous species have been rejected and are understood to be synonymous with ''O. humifusa''.

Characteristics that can potentially vary from colony to colony, or even between nearby plants in the same colony, include the height of the plants, the prevailing growing habit, the shape of the cladodes, the thickness of the cladodes, the presence of spines or glochids or the lack thereof, the color of spines and glochids and the color the flowers.

Because almost every outward trait of the cactus can vary so significantly in appearance, it is possible to find two plants living in close proximity which appear as if they are indeed entirely different species.  Typically, though, plants from two different colonies on two different habitat types (especially a cactus from a coastal colony as compared to a cactus from an inland colony) will exhibit the greatest divergence in appearance from each other.  It has been suggested that, due to the fragmented distribution of ''O. humifusa'' on isolated swaths of habitat, each disjunct colony may possess unique genetic traits that differ from those found elsewhere.