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.

Russian KnapweedCentaurea repens L.

Sunflower family - Asteraceae

Photo from Montana Weed Control Association

Toxic

Branch

Bulb

Bloom

Bloom

Patch

Photos from Montana Weed Control Association

Video Supplied By Montana Weed Control Association

Attribute	Description
Toxicity	Toxic. Horses.
Growth Habit	Perennial herb, up to 3 ft. tall, erect, may be in dense clumps; grayish color.
Leaves	Alternate, simple, of several types: upper leaves—small, narrow, unbroken edge; stem leaves—intermediate in size, slight toothed margins; basal leaves—deeply notched.
Stem	Numerous branched, each ending with a single flower.
Flower	Single, terminal, lavender, thistle-like, scaly seed head.
Roots	Dark brown to black and heavily scaled.
Seeds	Flattened, ivory colored, retained in cup-shaped seed heads.
Reproduction	Seeds and creeping rootstocks.
Habitat	Grazing land, grain and other crops, waste places, roadsides, river banks, and irrigation ditches.
Biological Controls	Russian knapweed gall nematode (Subanguina picridis).
Herbicides	Tordon, Curtail, Transline, Telar, Milestone.