Opuntia macrorhiza (Plains Prickly Pear Cactus, cousin to O. fragilis, the Brittle Prickly Pear).

This species grows in large mats in sand prairies, like Spring Green Prairie, and on Wisconsin River banks and dunes.  Many years ago a friend gifted me a few pads, which, she said, were descendants of a Wisconsin River pad given to her years prior.  I brought about a dozen from my garden to fill in a Pleasant Valley cabin planter at least ten maybe 15 years ago.  I just tucked the pointy end of each pad into the poor, shallow soil and added a little water.  Easy.  Well…  They thrived!  The entire area is now overflowing, and they bloom wildly every year at the end of June.  The long spines and smaller, sharp, detaching prickles (glochids) have kept ground squirrels and interns from nibbling.  That said, the big red fruits called “tuna” or “cactus figs” are sweet and delicious, if you don’t mind a mouthful of marbly seeds with each bite.  The mature pads are also edible and can be fried, baked, or pickled.  The glochids and spines should be washed or pealed away from fruit and pad first though to avoid damage to your lips, tongue and throat.

Prickly Pear species are only native to the Americas and are tolerant of extreme cold.  During the 16th century they were introduced into Europe and are now also found in Africa, Hawaii etc.  In many places they became an invasive weed, notably in Australia, where farmers were driven from their land, calling this cactus a “green hell.”  Some abandoned houses were crushed under the weight of the prickly pear mats, which grew across as much as a million acres per year, according to Wikipedia.  

One woman’s native species can be another’s headache.