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Yellow-Starthistle

(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 Location 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. Larger image.

yellow starthistle plant in bloom
Yellow Starthistle Plant

Video Information


Weed Images

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

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

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