Biennial or perennial 3-8 dm; basal lvs oblanceolate or obovate to lyrate; cauline lvs once or twice pinnately divided, the divisions often laciniate; heads 3 cm thick, blue, pink, or white; achenes 4 mm, deeply ribbed-sulcate; corona 1.5 mm, ca 24-veined; 2n=16. Native of Europe, n. Afr., and w. Asia, rarely adventive in our range. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.