Heads radiate (in ours), the rays yellow, pistillate (in ours); invol bracts ±numerous, subequal to imbricate, generally greenish at least distally; receptacle flat or somewhat convex, naked; disk-fls perfect but sometimes sterile; style-branches flattened, with ovate to subulate, sometimes very long, externally short-hairy appendage; achenes 4-5-angled or striate; pappus of numerous capillary bristles, these unequal but not divided into distinct long inner and short outer series; taprooted herbs (ours) or shrubs with alternate, simple to pinnatifid lvs and medium-sized to rather large heads. (Aplopappus, Isopappus, Prionopsis, Sideranthus) 150, New World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.