• Purple Starthistle Plant 215x150

Category A Weed

Sunflower family (Asteraceae)

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Purple starthistle (Centaurea calcitrapa)


    • Up to 4 ft. tall, stiff, highly branched, bushy and covered with hairs; NO wings on upper stems


      • Alternate; 4-8 in. long, mostly pinnate-divided, covered with short grayish hairs and dotted with resin


        • Pink to purple, each located at the tip of a branch; base of flower is vase-shaped, 0.75-1 in. long, 0.25 in. wide and covered with stout, straw-colored spines 0.4-1 in. long


          • Deep, stout taproot


            • Grows best in sites with heavy, fertile soils; often infests rangelands, waste areas and roadsides; known to occur in Pershing County

            • Annual, biennial or perennial; reproduces by seed; older rosettes have a circle of strawcolored spines at the center

            • Closely resembles Iberian starthistle in everything except seed; seed of Iberian starthistle has plume of bristles extending from one end, purple starthistle does NOT


              • Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; DO NOT burn

              • Apply 2,4-D, clopyralid or dicamba in the (rosette) stage; apply picloram from (rosette) through mid-bolt stage