Scientific name: Centaurea solstitialis

What Is It?

Yellow starthistle is a plant that grows to be 1-3 feet tall, with yellow, thistle-like flowers. It grows in rangeland, edges of cropland, abandoned farmlands and pastures, roadsides, railways, and recreational areas. Yellow starthistle can poison and kill horses.

Is It Here Yet?

Yes. Yellow starthistle is widespread in eastern Washington and found in a few locations in western Washington.

Why Should I Care?

Yellow starthistle provides poor and potentially damaging forage to cattle, and may poison or kill horses that ingest large quantities over short periods of time. Removal of seeds contaminating crops and feed is expensive. Recreation lands are becoming increasingly infested.

How Can We Stop It?

Promote native or desired species to help prevent or limit initial infestations. Clean your vehicles and equipment before moving them from an infested or potentially infested area. Yellow starthistle is listed as a Class B noxious weed in Washington, meaning it is designated for control in certain state regions. Contact your county noxious weed coordinator for assistance.

What Are Its Characteristics?

  • Grows to be 18-36 inches tall, with a deep taproot.
  • Has alternate leaves with bases extending downward, producing a winged effect.
  • Stems are dull green and covered with woolly hairs.
  • Yellow flowers are thistle like, with short yellowish spines in star-like arrangement at the base of the flower head.

Additional Photographs