Rhizomatous perennial 3-6 dm; stem villous-tomentose at least above; lvs glabrous or nearly so, linear or lance-linear, 3-10 cm נ2-6 mm, sessile, acuminate, closely and rather shallowly serrate to subentire; heads several or numerous in an open-corymbiform infl, the disk 4-8 mm wide; invol 4-5 mm; rays commonly 8-10, white, 3-5 mm; disk-fls 50-75; 2n=18. Beaches, roadsides, and waste places; native to n. Eurasia, naturalized in ne. Amer. from Lab. to N.Y., w. to Minn. and Mo. July-Sept. Forms escaped from cult. often have numerous rays.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.