This Class B noxious weed has a limited distribution in western Washington, and control is required in King County. Yellow starthistle is widespread in eastern Washington, with the largest infestations found in southeast and south central Washington and in the northeastern part of the State. In King County it is occasionally found on I-90 and in Port of Seattle property.

Yellow starthistle is a winter annual that is about 12" to 36" tall. It has yellow thistle-like flowers with long, yellowish spines beneath the flower head. The stems and leaves are a dull green and covered with fine wooly hairs. This plant spreads by seed, and each plant can produce 150,000 seeds. This plant is very adaptable and can establish in nearly all semiarid or sub-humid rangelands.

For more information about yellow starthistle, please follow this link to the Washington State Noxious Weed Control Board.

Read an informational Centaurea brochure (316 KB Acrobat file, 46 seconds on 56K modem).

If you find yellow starthistle in King County, please notify us through our online infestation form.

To find out where we have records of this weed in King County, use our interactive noxious weed map and search for yellow starthistle.