Yellow Starthistle

Centaurean solstitalis L.

Family: Asteracacea (Sunflower)

Class B Noxious Weed

Control or Containment Required

Yellow starthistle is a Class B Noxious Weed that originated in the Mediteranean area and Asia. As a winter annual, it germinates in the fall, over-winters as a seedling, flowers in spring and summer, then produces seeds and dies. 

Seedlings resemble dandelions with deeply lobed leaves. Mature plants have a gray-green appearance with winged stems, growing about 2 to 3 feet tall. It has solitary yellow flowers at the ends of stems with sharp spines beneath the flowers.

Yellow starthistle invades roadsides, field edges and overgrazed rangelands. If untreated, this highly competitive noxious weed crowds out native vegetation and desirable forage. It produces a toxin that can cause fatal "chewing disease" in horses.