State Noxious Weed List - Yes

Growth form - Winter annual or biennial, spreading only by seed. Often grows in excess of 6 feet tall. Easily identified by the very large flower heads (2 to 3 inches across) that tend to droop. The flower is generally rose to violet, rarely purple and has very characteristic brown bracts that resemble a pine cone. Stems are usually very branched with spiny wings; however, the wings are interrupted and not complete along the stem. The leaves are oblong to lanceolate, lobed to four-fifths of the width with slender spines on the margin. Each lobe ends in a spine.

Two subspecies which differ in flower size and pubescence occur in North Dakota.  

Musk thistle produces more than 10,000 seeds per plant. The achenes are light brown with stripes and a light apical rim. Rosettes have a light green midrib and can grow 2 feet in diameter or more.