Coarse, erect perennial to 1 m or more from fascicled roots, usually simple to the infl; lvs linear, much elongate, parallel-veined, entire or remotely spinulose, the lower to 8 dm × 3 cm, the upper gradually reduced; heads round-ovoid, 1-2 cm long and thick; bracts lance-ovate, entire or nearly so, cuspidate, rarely projecting from beneath the head; bractlets similar but smaller; 2n=96. Moist or dry sandy soil, open woods, and prairies; s. U.S., n. to Va., Ind., Minn., and Kans., and occasionally adventive farther north. July, Aug. (E. aquaticum, misapplied)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.