Milk Thistle is native to the Mediterranean regions of Europe, North Africa and the Middle East.

Milk thistle is a thistle of the genus Silybum, a flowering plant of the daisy family (Asteraceae). The name "milk thistle" derives from a feature of the leaves, which are prominently banded with splashes of white.

Milk thistle has active flavanoid-lignan (flavanolignan) group of constituents, called silymarin, contained only in the seed shell.