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Yellow starthistle

Quick facts

Yellow starthistle is a Prohibited Noxious Weed (Eradicate List) in Minnesota. All above and below ground parts of the plant must be destroyed. No transportation, propagation, or sale of this plant is allowed.

  • Yellow starthistle prefers open sunny areas.
  • An established plant that germinates quickly under varying conditions.
  • Outcompetes native vegetation for space and resources.
  • Grazing animals will eat it until it bolts and develops large spines.
  • Toxic to horses.

Yellow starthistle should be reported. Report yellow star thistle by emailing "Arrest the Pest " or calling 651-201-6684 (metro) or 1-888-545-6684.

How to identify yellow starthistle

  • An annual plant that grows up to two to three feet.

Stem

  • The stems of mature plants are rigid.
  • They spread and branch from the base.
  • Stems and leaves are covered with a loose, cottony wool that gives them a whitish appearance.

Leaves

  • Rosette leaves resemble dandelions due to their lobed, flat appearance and woolly hairs.
  • Leaves found on the upper part of the plant are short and narrow.

Flowers

  • Golden yellow flower heads are about a half inch in diameter.
  • Fertilization is highly dependent on various pollinators.
  • Flowers have two inch long straw-colored spines.
  • Blooms from May to September.

Seeds

  • Seeds found in the center of the seed head have white fluffy hairs.
  • Seeds near the seed head edge do not have white fluffy hairs.
  • Seeds survive in soil for up to 10 years.
  • A single plant can produce 100,000 or more seeds under ideal conditions.

Roots

  • Deep taproot grows rapidly in winter and early spring months.

 

Yellow starthistle flowers
Yellow starthistle flowers

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

Reviewed in 2019

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