Rhizomes pubescent. Aerial stems dimorphic. Sterile stems green, 10-80 cm × 1-5 mm, usually regularly branched with lateral branches simple; ridges nearly smooth; grooves (4)-6-14; sheaths green, up to 10 mm long, teeth as many as grooves; central hollow < 1/2 diam. of main stem; main stem occasionally bearing terminal cones in mid-summer. Fertile stems normally appearing in spring before the sterile stems and dying after shedding spores, pale brown, usually smaller than sterile stems, not branched; sheaths pale brown with darker teeth, up to 14 mm long. Cones (4)-10-40 mm long.