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University of Minnesota Extension

Plumeless thistle

Quick facts

Plumeless thistle is an invasive species. Plumeless thistle is on the Control noxious weed list meaning you must prevent the spread of this plant.

  • Plumeless thistle is most commonly found on highly disturbed sites and pastures.
  • It replaces native species quickly.
  • Plumeless thistle reduces desirable forage species.

Plumeless thistle should be reported. The Minnesota Department of Natural Resources provides detailed recommendations for reporting invasive species.

tall, plumeless thistle plant in the grass

How to identify plumeless thistle

  • Plumeless thistle (Carduus acanthoides) is a biennial herbaceous plant that grows up to six feet tall.
  • Often has a basal rosette for the first year and bolts the second.


  • Branched stems have vertical leafy wings with spines on the tips and are covered with many spiny leaves.
  • Plant produces one to several flowering stocks when it bolts.
  • Flower stems are branched with spiny wings extending to the flower heads.


  • Rosettes are four to eighteen inches wide, with deeply lobed, woolly, spiny leaves.
  • Bolted plant leaves are wavy, spiny, with hairy underside; long near the base and diminish in length as they ascend the plant.
  • Leaves are narrower and wavier than musk thistle.
  • The spiny leaves extend onto and around the stem, giving it the appearance of clusters of leafy spines throughout the plant.


  • Small (one inch diameter), purple-pink singular or clustered flower heads contain many tiny individual flowers; can be bulbous shaped.
  • Blooms May to August.


  • Small, oblong, slightly curved seeds, about 0.12 inches long are contained inside a thin-walled fruit.
  • They are loosely attached with tuft of hair.


  • Taproot
close up of three plumeless thistle blossoms with leaves
Plumeless thistle leaves
single pink plumeless thistle flower
Plumeless thistle flower



Angela Gupta, Extension educator; Amy Rager, Extension educator; Megan M. Weber, Extension educator

Reviewed in 2019

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