This stout thistle usually grows in dry, sunny areas. The stem branches at the top, and it reaches a height of 4 to 10 feet. The leaves are wide, with white blotches or veins. The flowers are red-purple. The small, hard-skinned fruit is brown, spotted, and shiny.
Milk thistle is easy to grow, and it matures quickly, in less than a year.
Milk thistle products are made from the seeds inside the fruit. The seeds contain 1.5 percent to 3 percent silymarin. Silymarin is actually made up of a group of compounds called flavonolignands. Other flavonolignans in silymarin are isosilybin, dehydrosilybin, silydianin, and silychristin. Several teas contain the standardized extract.