Although much of the pad appears smooth, you better not touch.

Purple Prickly Pear Cactus (Opuntia violacea)
Desert: Chihuahuan
Height: Up to 3.5 feet
Pads: Oblong, bluish purple, with long black or white spines
Flowers: Yellow with red centers
Fruit: Oval to 1.5 inches, green
Elevation: 3,000-5,500 feet

Like other cactus, most prickly pears and chollas have large spines -- actually modified leaves --
growing from tubercles -- small, wart-like projections -- on their stems. But members of the
Opuntia genus are unique because of their clusters of fine, tiny, barbed spines called glochids.
Found just above the cluster of regular spines, glochids are yellow or red in color and detach
easily from the pads. Glochids are often difficult to see and more difficult to remove, once lodged
in the skin.