Stems all alike, evergreen, ascending or erect, 1-3 dm, 1-2.5 mm thick, branched near the base, 5-12-ridged, the ridges shallowly furrowed and with 2 rows of siliceous tubercles; central cavity 1/4-1/3 the diameter of the stem, mostly larger than the 5-12 vallecular ones, stomates in 2 rows in each principal furrow; sheaths mostly 2-5 mm, poorly marked at the base, slightly flared upwards, green, with an apical blackish band, the body of each tooth 1-2 mm with a black or blackish, 2-ridged midstripe and conspicuous white-hyaline margins, rather abruptly contracted to a hair-like deciduous tip 0.5-1 mm; cones small, scarcely 1 cm, subsessile, apiculate. Wet thickets, bogs, and sandy shores; circumboreal, in Amer. s. to Pa., Ill., Minn., and Colo. Ours is var. variegatum.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.