Aerial stems dimorphic; vegetative stems brownish to green, branched, 25--70 cm; hollow center 1/6--1/3 stem diam. Sheaths squarish in face view, 3--6 × 2.5--6 mm; teeth reddish, 8--18, papery, 3--10 mm, coherent in 3--4 large groups. Branches in regular whorls, delicate, arching, branched, solid; ridges 3--4; valleys channeled; 1st internode of each branch longer than subtending stem sheath; sheath teeth attenuate. Fertile stems brown, with stomates, initially unbranched, persisting and becoming branched and green after spore discharge. 2 n =216. Cones maturing in late spring. Moist forests; 0--2800 m; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Conn., Del., Idaho, Iowa, Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.Dak., Ohio, Pa., R.I., S.Dak., Vt., Va., Wash., W.Va., Wis.; Europe; n Asia to ne China, Japan in Hokkaido.

Stems annual, dimorphic, the sterile ones 3-7 dm, 1.5-3 mm thick, mostly 10-18-ridged, each ridge with 2 rows of sharp hooked spinules, the stomates in 2 bands in the furrows, the central cavity larger than the vallecular ones and most more than half the diameter of the stem, the sheaths 1-2 cm, basally green, distally brown, with persistent, irregularly connate brown teeth; branches regularly whorled, solid, 4-5-angled, commonly again branched; the first internode commonly longer than the associated sheath of the main stem; fertile stems subprecocious, at first simple and pale, later producing whorls of green, mostly compound branches and often themselves becoming green; cones long-peduncled, 1.5-3 cm, deciduous, not apiculate. Cool moist woods; circumboreal, in Amer. s. to Md., W.Va., Ky., and Io.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.