Botanical Name Silybum marianum Whole milk thistle seeds are obtained from Silybum marianum a Mediterranean herb commonly called Holy Thistle Ladys Thistle and Blessed Thistle While the seeds are most frequently used to make teas tinctures and infusions they can also be as food Milk thistle Silybum marianum L Gaertner Asteraceae is an annual or biennial that grows from 5 10 feet 15 30 m tall has large pricklyedged leaves covered with undulating white patches and stems containing a milky juice