Glabrous annual or biennial, 3-15 dm; lvs to 15 cm, pinnately parted, with mostly 3-7 lance-linear to linear, incised-dentate to entire, acute or acuminate segments; petioles 0.3-1.5 cm; heads radiate, with ca 8 rays 1-2.5 cm, the disk 8-15 mm wide; invol glabrous or nearly so, the 6-10 outer bracts linear or linear-spatulate, sometimes ciliate-margined, very rarely exceeding the disk; achenes flat or nearly so, narrowly cuneate-oblong or the inner cuneate-linear, mostly 5-9 mm and 2.5-4 times as long as wide, dark, smooth or hairy, the margins antrorsely ciliate; pappus of 2 short, erectly setose strong awns or awn-scales mostly 1-2 mm (seldom obsolete); 2n=24. Wet places; Mass., s. Ont., n. Wis., and e. Minn., s. to N.C., Ky., and Neb. Aug.-Oct. (B. trichosperma)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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