Silybum marianum, colloquially identified as Carduus marianus, known as milk thistle, is an annual or biannual plant of the Asteraceae family. This fairly typical thistle has red to purple flowers and shiny pale green leaves with white veins. Originally a native of Southern Europe through to Asia, it is now found throughout the world. The medicinal parts of the plant are the ripe seeds.
Possibly native near the coast of south east England.It has been widely introduced outside its natural range, for example into Iran, North America, Australia, and New Zealand where it is considered an invasive weed.
The biosynthesis of the flavonolignan silymarin, a constitutive compound of the fruits of Silybummarianum with strong antihepatotoxic and hepatoprotective activities, is severely reduced in cell cultures of this species.  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.