Perennials, 50-100+ cm. Stems (from short caudices or rhizomes) single, sparsely branched distally, 5-10+ dm, glabrous or glabrate proximally, puberulent distally (among heads). Leaves usually opposite (distal sometimes alternate); simple, sessile; blades pinnately nerved, lanceolate to oblong, 70-150+ × 10-30 mm (lengths mostly 2-5 times widths), bases truncate to somewhat rounded, margins serrate, apices narrowly acute to acuminate, faces glabrate (scattered, fine hairs), gland-dotted. Heads in corymbiform arrays. Phyllaries 10-15 in 2-3 series, elliptic to oblong, 2-5 × 0.5-1.5 mm, apices rounded to acute (not mucronate), abaxial faces villous to puberulent, gland-dotted. Florets 5; corollas 3-3.5 mm. Cypselae 2-3 mm; pappi of 30-40 bristles 3-4 mm. 2n = 20, 30.
Plants 6-15 dm, single-stemmed from a crown or short caudex, puberulent in the infl, the herbage otherwise glabrous except that the lvs are gland-dotted; lvs opposite, sessile or subsessile, lanceolate, usually broadly rounded at the base, serrate, acuminate or long-acute, mostly 7-18 נ1.5-5 cm, 2.5-7 times as long as wide, the venation strictly pinnate; invol 4.5-6.5 mm, its bract imbricate, broadly rounded to merely obtuse, villous-puberulent and usually also atomiferous-glandular; fls 5(6), white; 2n=20, 30. Woods, especially in sandy, acid soils; s. N.H. to se. Minn., s. to Ga. and Ark. Aug., Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.