Yellow Starthistle

Yellow starthistle stem and flower bud.
Field of Yellow starthistle.
Yellow starthistle flower.

Yellow Starthistle

(Centaurea solstitialis)

Information Sheet (PDF)

Colorado List A - Eradication required 

General

  • Family: Sunflower (Asteraceae)
  • Introduced from South America and Europe

Habitat

  • Annual forb
  • Found in rights-of way, disturbed sites, and rangeland

Plant

Vegetation

  • Leaves ½ inch wide and 2-4 inches long
  • Basal leaves dry up as the plant begins to bolt
  • Stems are winged
  • Short grayish hairs on the leaves and stems
  • Plants up to 3 ½   feet tall

Roots

  • Taproot to 3 feet long

Flower

  • ½ - 3/4 inch wide
  • Bracts covered with spines, center spine 
  • Color: Yellow
  • Season: May to October
  • Single at end of stems

Seed

  • Up to 100,000 per plant 

Reproduction

  • Seed

Control

Biological

  • None

Chemical

Cultural

  • Prevention
  • Removal - make sure the entire root is removed. Must be repeated as new plants germinate

Mechanical

  • Burning - N/A
  • Grazing - N/A - Poisonous to horses
  • Mowing - N/A

Use all chemicals according to the manufacturer's label. No specific recommendation or endorsement is made or implied by listing methods or products.