Serving Montana Agriculture and growing prosperity under the Big Sky


(Centaurea solstitialis)

Yellow Starthistle

(1A, not present in Montana)

(Centaurea solstitialis)

Quick ID
  • Similar looking flower to other knapweeds, but bright yellow, and with sharp, spiny bracts
  • Hairy leaves, giving the plant a grayish green color
  • Upper leaf bases extend down the stem to produce a fin or winglike appearance
Yellow Starthistle Map

Map Courtesy of Montana Natural Heritage Program, Yellow Starthistle - Low Suitability: 12% of Montana, Moderate: 9%, Optimal:4%. All observation points were eradicated and the plant is currently not found in Montana. Click here for larger image.

yellow starthistle plant
Yellow Starthistle Plant

Video Information

Weed Images

Yellow Starthistle Plant - Photo by Steve Dewey, Utah State University,
Yellow Starthistle Rosette - photo by Steve Dewey, Utah State University, Bugwood.o
Yellow Starthistle flower
Yellow Starthistle Stem - photo by Ellen (Mel) Harte,
Yellow Starthistle Spines - Peggy Greb. USDA Agricultural Research Service,
Yellow Starthistle Mature - Photo by Cindy Roche,
Yellow Starthistle - Photo by Steve Dewey, Utah State University,

Weed Specifications

Weed Info
Type Information
Toxicity Toxic to horses, causing a fatal nervous order called chewing disease with no known treatment
Best Management Practices

Herbicide, repeated mowing after bolting, controlled burning, targeted grazing with goats or sheep before flowers and spines form, biocontrol, pulling or digging on a small scale before flowering; weed free hay, seed, equipment, ATVs, etc.; maintain healthy landscapes, continued prevention

*See additional documents below
Habitat Roadsides, rangeland, abandoned cropland, disturbed areas, trails, often occurring on south-facing slopes
Root Very deep taproot
Leaves Dandelion-looking rosette with lobed leaf margins, stem leaves narrower and their bases extend down the stem, giving them a fin or winglike appearance
Lifespan Winter annual, germinating in the fall and maturing the following spring and summer, but sometimes germinates in the spring
Similar Looking Plants Rosettes resemble dandelions, mustards, or other knapweeds
Important Information Only reproduces by seed, with each plant capable of producing tens of thousands of seeds, seeds typically remaining viable for 3-5 years, but sometimes for more than twice that long; spines painful to humans, wildlife, and livestock, reducing recreation opportunities, degrading plant communities, and diminishing productive habitat; yellow starthistle is a Montana success story, thus far being identified and eradicated before it has been able to become established

Become a Early Detection, Rapid Response Partner

Report the Weed

Find Out More...

To Report, Contact: