Opuntia macrocentra or Black-Spined Prickly Pear

"Opuntia macrocentra", the long-spined purplish prickly pear or purple pricklypear, is a cactus found in the lower Southwestern United States and Northwestern Mexico. A member of the prickly pear genus, this species of "Opuntia" is most notable as one of a few cacti that produce a purple pigmentation in the stem.