Extension Logo
Extension Logo
University of Minnesota Extension
https://extension.umn.edu

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.

many yellow starthistle growing in the grass

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.

 

close up of many yellow starthistle flowers
Yellow starthistle flowers
single yellow starthistle flower
Yellow starthistle flowers

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

Reviewed in 2019

Share this page:

© 2019 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer.