Erect, fibrous-rooted perennial to 1 m, branched above; lvs elongate, pinnately net-veined, linear to lance-oblong, the lower long-petioled, 1-3 dm, the upper smaller and less petiolate, varying from entire to spinulose-toothed or even pinnatifid; bracts spreading or deflexed, mostly exceeding the heads, entire to spinose-serrate or pinnatifid; heads shortly ovoid-cylindric, 1-1.5 cm; bractlets trifid above and spinulose-tipped; 2n=16. Bogs and marshes near the coast; N.J. to ne. Fla. July-Sept. (E. virginianum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.