yellow starthistle

Asterales > Asteraceae > Centaurea solstitialis L.
Synonym(s): yellow star thistle, yellow star-thistle

Yellow starthistle is an annual that can grow from 0.25 - 3 ft. (0.1-1 m) in height. Leaves near the base are petiolate, dissected, 2-6 in. (5-15 cm) long and usually absent at time of flowering. Leaves further up the stem are decurrent, entire and 0.4-4 in. (1-10 cm) long. Flowering occurs from June to October, when yellow flowers appear in heads at the tips of the branches. Bracts that subtend the flower head have a small cluster of spines and a stout central spine 0.4-1 in. (10-25 mm) in length. Yellow starthistle was accidentally introduced into the United States in the mid- 1800s as contaminate of alfalfa seed. Yellow starthistle invades woodlands, pastures, roadsides and fields.


Identification, Biology, Control and Management Resources

  • Weeds of the Week - USDA Forest Service, Northeastern Area, Forest Health Protection

Selected Images from Invasive.org

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Plant(s); Seedling stage
Cindy Roche, , Bugwood.org
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Plant(s); Bolting stage
Cindy Roche, , Bugwood.org
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Plant(s); Rosette
Steve Dewey, Utah State University, Bugwood.org
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Foliage;
Steve Dewey, Utah State University, Bugwood.org
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Plant(s); Spines are equal to or greater than 45° angle from stem
Cindy Roche, , Bugwood.org
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Flower(s);
Steve Dewey, Utah State University, Bugwood.org
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Flower(s);
Peggy Greb, USDA Agricultural Research Service, Bugwood.org
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Feature(s); Spines
Steve Dewey, Utah State University, Bugwood.org
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Fruit(s);
Cindy Roche, , Bugwood.org
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Plant(s); in flower
Charles Turner, USDA Agricultural Research Service, Bugwood.org
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Plant(s);
Steve Dewey, Utah State University, Bugwood.org
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Infestation;
Steve Dewey, Utah State University, Bugwood.org
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Infestation; example of yellow starthistle infestation suitable for a biological control program
University of Idaho Archive, University of Idaho, Bugwood.org
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Infestation;
Steve Dewey, Utah State University, Bugwood.org
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Infestation;
Steve Dewey, Utah State University, Bugwood.org
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Dispersal; Invasive plants can be spread far and wide by people and as hitchhikers on vehicles.
Jerry Asher, USDI Bureau of Land Management, Bugwood.org
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Diagram or Graphic; Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 3: 560.
USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org
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Invasive Reference(s):

Check Invasive.org for most current lists.
  • Arizona - Noxious Weed Law
  • California - Noxious Weed Law
  • California - Invasive Plant Inventory
  • Colorado - Noxious Weed Law
  • Montana - Noxious Weed Law
  • New Mexico - Noxious Weed Law
  • Nevada - Noxious Weed Law
  • North Dakota - Noxious Weed Law
  • Oregon - Noxious Weed Law
  • South Dakota - Noxious Weed Law
  • Texas - Invasive Plant List
  • Utah - Noxious Weed Law
  • Washington - Noxious Weed Law
  • Mid-Atlantic - EPPC List
  • Invasive Plants: Western North America
  • Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species
  • Invasive Plants of the Upper Midwest


External Links


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