Milk thistle is a plant that is native to Europe and was brought to North America by early colonists. Milk thistle is now found throughout the eastern United States, California, and South America. The plant grows up to 2 meters high and has large, bright purple flowers.
Milk thistle gets its name from the milky sap that comes out of the leaves when they are broken. The leaves also have unique white markings that, according to legend, were the Virgin Mary's milk. The above ground parts and seeds are used to make medicine. The seeds are more commonly used.