Barry Rice, sarracenia.com, Bugwood.org

Red (Purple) starthistle

Centaurea calcitrapa

Red (Purple) starthistle (Centaurea calcitrapa) is an invasive plant. It is a native of Europe and was first detected in Washington in 1989.

Centaurea species may produce allelopathic effects and are highly competitive with other plants, often displacing desired vegetation.