Very densely cespitose, forming large tussocks; stems 2-7 dm; lvs clustered at base, with filiform blade 1 mm wide; 1 or 2 dilated, bladeless sheaths mostly below
the middle of the stem; spike solitary; basal sterile scales 10-15, lance-ovate, blackish, long-acuminate, with white or pale margins, spreading or reflexed at maturity; bristles white or seldom brownish or reddish; anthers 2-3 mm; achene distinctly obovate, 2.5-3.5 mm, slightly over half as wide, minutely (0.1-0.2 mm) apiculate; 2n=58, 60. Bogs and open conifer-swamps; circumboreal, s. to N.J., Pa., and n. Ind., and Alta. Fr Apr.-July. (E. callithrix, misapplied) Our plants are var. spissum (Fernald) B. Boivin. (E. spissum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.