Mostly biennial, 3-10 dm; lvs elongate, generally tapering fairly uniformly from base to apex, not recurved, evidently floccose when young, later ±glabrate except commonly in the axils; peduncles evidently enlarged and fistulous under the heads in fl and fr; invol bracts typically 13, down to 8 on later heads or small plants, 2.5-4 cm in fl, distinctly surpassing the rather pale lemon-yellow rays, elongating to 4-7 cm in fr; achenes slender, 25-36 mm, gradually narrowed to the stout beak; pappus whitish; 2n=12. Roadsides and other open, relatively dry places; native of Europe, now widely established over most of the U.S., especially westward. May-July. (T. major)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.