In much of west Texas, the iconic Prickly Pear cactus — with its plum-like fruit and forbidding spiked pads — is at best considered a nuisance, and at worst a downright hazard to livestock. But in most of the rest of the semi-arid world — from Mexico and Chile, large swaths of India and South Africa, as well as Spain and Morocco — Opuntia ficus-indica (Prickly Pear) is used in dye-making, as feed for livestock, and, little by little, as feedstock for anaerobic biogas production.