The Mission of the Yellowstone County Weed Department is to assist the public, private, and other government agencies to manage and control existing noxious weed infestations as well as to prevent new invasive species from infesting Yellowstone County.

Scotch ThistleOnopordum acanthium

Attribute	Information
Growth Habit	Biennial that grows up to 12 feet.
Leaves	Large, spiny, and covered with fine dense hair.
Stem	Broad, spiny wings.
Flower	Flower heads are numerous, 1 to 2 inches in diameter, bracts spine-tipped. Flowers are violet to reddish.
Roots	—
Seeds	—
Reproduction	—
Habitat	Native of Europe and eastern Asia and is now sparsely naturalized over much of North America.
Biological Controls	—
Herbicides	Milestone