• Scotch Thistle Plant 215x150

Category B Weed

Sunflower family (Asteraceae)

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Scotch thistle (Onopordum acanthium)


    • Up to 12 ft. tall and branched, with spiny wings along smooth stem; covered with wooly, gray hairs


      • Alternate; oblong, 4-20 in. long, covered with wooly, gray hairs giving plant a gray-green appearance; edges (margins) are lobed or toothed with stiff spines


        • White to purple flowers, each located at the tip of a branch; base of flower is round (resembles a squashed globe), 1-2 in. wide and covered with green, purple or yellow bracts (less than 0.2 in. long), each tipped with a spine; often covered with wooly, gray hairs


          • Fleshy taproot


            • Often infests pastures, rangeland, roadsides and waste areas; known to occur in all Nevada counties

            • Biennial; reproduces by seed

            • Forms dense stands that are difficult for humans and animals to penetrate


              • Hand-removal, digging or mowing prior to flowering can be effective

              • Apply 2,4-D, dicamba, chlorsulfuron, metsulfuron or picloram to actively growing rosettes; 2,4-D + dicamba, aminopyralid, chlorsulfuron or clopyralid between rosette and late-bolt stage