Opuntia macrorhiza

Vestigial leaves on Opuntia macrorhiza – plains prickly pear cactus. The leaves are the spikes that stick out of the central, greenest pad. Identification and tutelage courtesy of Ronald Wittmann, coauthor of Colorado Flora. Mr. Wittmann adds, “Opuntia leaves are deciduous. They persist for a few weeks then drop. … O. macrorhiza is the most common species on the eastern plains of Colorado and certainly deserves mention [in the Wikipedia article on Opuntia]. O. ficus-indica is cultivated for its fruits in warm climates throughout the world.”