At the centre of Mexican national and religious identity stands a cactus: the Mexica (Aztecs) were told by their god Huitzilopochtli to build their city where they found an eagle perched on a nopal, a prickly-pear cactus, growing from a rock in the lake, the sign they found at what became Tenochtitlan, and the image at the heart of the modern flag of Mexico. The prickly pear itself was sacred and sustaining, its fruit and pads a staple food, and its cochineal insects a treasured dye. In folk practice cacti are grown by doorways as guardians, their spines turning away harm. Endurance, protection and the founding of a nation gather to a spined desert plant.
Modern archaeology has confirmed the historical core of the founding story: excavations of the Templo Mayor in the heart of Mexico City, begun in the 1970s, uncovered the remains of the Aztec sacred precinct built at the very site the chroniclers describe, giving the eagle-on-the-cactus legend a genuine, excavated city beneath it rather than only a painted page. Many wild cactus species face a real and current threat from illegal poaching for the ornamental plant trade, and a large share of cactus species are now assessed as threatened or endangered, with international trade in wild specimens restricted under CITES, a modern regulatory fact that sits alongside the plant's old symbolism of endurance and survival.