Milk Thistle. Photo by Chris Kilham

Milk Thistle

Milk thistle, or Silybum marianum, is native to southern Europe and southern Russia, and is common throughout North and South America, South Australia and Central Europe. Milk thistle is a biennial plant up to 10 feet in height, easily recognized by its brilliant reddish-purple flowers and large prickly leaves. The plant, most notably its seeds, contains a complex of therapeutic compounds known collectively as silymarin. Milk thistle has been employed as a medicine for at least 2000 years, primarily for ailments of the liver.