Silybum marianum milk thistle is a milk thistle, a plant of the Asteraceae family. The medicinal parts of the plant are the ripe seeds.

It has a large number of other common names, such as Marian Thistle, Mary Thistle, Mediterranean Milk Thistle and Variegated Thistle. .

In herbalism, it is used in cases of liver diseases (cirrhosis,jaundice and hepatitis ), gallbladder disease, and is claimed to protect the liver against poisons.

Its potent extract is used in medicine under the name silymarin. Another extract, silibinin or a derivative, is used against poisoning by amanitas, such as the Death Cap (Amanita phalloides) and the Fly Agaric.