Stems to 1.5 m, branched above and usually with some short axillary branches, ±hairy, especially above; lvs narrowly lanceolate, acute to acuminate, mostly with a few low teeth, the main ones 3-5 cm נ8-12(-15) mm, with 4-7 pairs of lateral veins; heads numerous, dense, 8-15(-20) mm thick; outer foliaceous bracts velvety above; inner bracts lanceolate, commonly surpassing the cals, conspicuously acuminate, thinly hairy on the back, densely ciliolate, with a conspicuous midvein; cal-lobes narrowly deltoid, 0.5-1 mm; 2n=76-78. Upland woods and thickets; Vt. to N.C., w. to Mich., Io., w. Kans., and w. Okla. The e. var. verticillatum, extending w. to Mich., O. and e. Ky., is not very hairy, the lvs hairy chiefly along the veins beneath. The more w. var. pilosum (Nutt.) Cooperr., extending e. to O. and s. Mich., is more hairy, the stem conspicuously spreading- pilose, the lower lf-surfaces evenly spreading-hairy, the cal ±shaggy. (P. pilosum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.