Nopales or Prickly pears typically grow with flat, rounded cladodes (also called platyclades) armed with two kinds of spines; large, smooth, fixed spines and small, hairlike prickles called glochids, that easily penetrate skin and detach from the plant. Many types of prickly pears grow into dense, tangled structures.
Like all true cactus species, prickly pears are native only to the Americas, but they have been introduced to other parts of the globe. Prickly pear species are found in abundance in Mexico, especially in the central and western regions, and in the Caribbean islands (West Indies). In the United States, prickly pears are native to many areas of the arid Western United States, including the lower elevations of the Rocky Mountains, where species such as Opuntia phaeacantha and Opuntia polyacantha become dominant, and especially in the desert Southwest. Prickly pear cactus is also native to the dry sandhills and sand dunes of the East Coast from Florida to Connecticut/Long Island (Opuntia humifusa). Further north, Opuntia occurs in isolated areas from the southern Great Lakes to southern Ontario. O. humifusa is also a prominent feature of the flora at Illinois Beach State Park, inWinthrop Harbor, Illinois, north of Chicago, and of Indiana Dunes State Park southeast of Chicago.