Coarse perennial herb to 2 m, the stem finely spreading-hairy; lvs irregularly and shallowly dentate, densely velvety-woolly beneath, sparsely spreading-hairy or subglabrous above, the lower long-petiolate and elliptic, with blade to 5 נ2 dm, the upper becoming ovate, sessile and cordate-clasping; heads few, pedunculate, large, the disk 3-5 cm wide, the invol 2-2.5 cm; outer bracts broad, herbaceous, densely short-hairy; inner bracts narrow, subscarious, glabrous; rays numerous, slender, 1.5-2.5 cm; achenes glabrous, columnar and ±distinctly quadrangular, multistriate; pappus-bristles united at base, often in groups; 2n=20. Intr. from Europe; cult., escaped, and sparingly naturalized in moist or wet disturbed sites. May-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.