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plumeless thistle

Scientific Name: Carduus

Family: Asteraceae

Category: Dicot

Growth:

Duration:

Other Names:

       

Spiny Plumeless Thistle (Carduus acanthoides)

Carduus acanthoides, commonly known as the spiny plumeless thistle, welted thistle, or simply plumeless thistle, is a biennial plant recognized as an invasive species in several regions.

Considerations for Pets

  • The stem and foliage are spiny, which could pose a physical hazard to animals.

Considerations for Children

  • The plant has spiny stems and foliage, potentially causing injury.

Taxonomy and Nomenclature

  • Scientific Name: Carduus acanthoides L.
  • Family: Asteraceae (also known as Compositae or Sunflower Family)
  • Common Names: Spiny plumeless thistle, welted thistle, plumeless thistle, bristly thistle
  • Belongs to the genus Carduus, considered one of the "true thistles."

Distribution and Habitat

  • Native to Europe and temperate Asia.
  • Found in the Northeast, Midwest, and many western states (excluding Oregon, Nevada, and Utah).
  • Also found in eastern North Dakota and western Virginia.
  • Habitat includes pastures, meadows, fields, highway median strips, and roadsides.

Ecological Role

  • Considered a prohibited noxious weed in Minnesota.
  • An invasive species that can form weedy, monotypic stands.
  • Crowds out desirable forage plants in pastures and meadows.
  • Livestock tend to avoid grazing in heavily infested areas.

Morphological Characteristics

  • Biennial forb (can also behave as a winter annual).
  • Grows to a height of 3-10 dm (approximately 1-4 feet), sometimes exceeding 2 meters (6.5 feet).
  • Possesses a stout, fleshy taproot.
  • Stems are freely branching and have spiny wings extending to the flower heads.
  • Leaves are wavy and have spiny bracts.
  • Distinguished from musk thistle by leaf-like spines on the stem and hairs on the underside of the leaf.
  • Purple flower heads are approximately 1 inch in diameter with spreading spiny bracts.
  • Abundant upper branching gives a "top heavy" appearance to mature plants.

Life Cycle

  • Winter annual or biennial.
  • Reproduces only by seed.
  • Flowering occurs from June to August.
  • Seed germination typically occurs in summer and fall, with the plant overwintering as a rosette.
  • A single plant can produce up to 120,000 seeds.

Interactions with Other Organisms

  • Hybridizes with other species.
  • Research has been conducted on biological control agents.

Further Information

  • Minnesota Noxious Weed Law: MN Statues 18.76-18.91.
  • Nebraska Weed Control Association: Provides detailed information on Plumeless Thistle.