USA. Milk Thistle (Silybum marianum) Seed, Whole, Certified Organic Common names: Marian Thistle, Scotch Thistle, Cardus Marianus, Blessed Milk Thistle, Cardo Blanco, Cardo de Burro, Chardonmarie, Shui Fei Ji, Lactuca Scariola, Prickly Lettuce, Dugadh Rom, Vanya Kahu Family: Asteraceae Milk Thistle is a spiny annual or biennial plant, bearing showy purple flowers similar to the Artichoke, that apparently originated in southern Eurasia (some say in southeast England, others in Crete), and can now be found in temperate zones throughout the world. It grows approximately 1 to 6 feet high, typically in disturbed areas, and is commercially cultivated in Europe, China, and South America.