Argemone mexicana (Mexican poppy, Mexican prickly poppy, flowering thistle, cardo or cardosanto) is a species of poppy found in Mexico and now widely naturalized in many parts of the world. An extremely hardy pioneer plant, it is tolerant of drought and poor soil, often being the only cover on new road cuttings or verges. It has bright yellow latex, and though poisonous to grazing animals, is rarely eaten, but has been used medicinally by many people including those in its native area, the Natives of the western US and parts of Mexico.