Heads disciform, whitish (in ours) or dull yellow; invol a single series of narrow, equal, ±herbaceous bracts, sometimes with a few bracteoles at base; receptacle flat, naked; outer fls pistillate, filiform-tubular, eligulate, in 2-several series; inner fls perfect but sometimes sterile, the cor narrowly tubular, 4-5-toothed; style-branches flattened, truncate or with a very short hairy appendage; achenes 5-angled or 10-20-nerved; pappus of numerous slender bristles; erect herbs with alternate, entire to pinnately dissected lvs and cylindric to ovoid heads. 12, N. and S. Amer. and Australia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.