Aerial stems lasting less than a year, occasionally overwintering in the southwestern United States, usually unbranched, 20--150 cm; lines of stomates single; ridges 10--32. Sheaths green, elongate, 7--15 × 3--9 mm; teeth 10--32, articulate and usually shed early, leaving dark rim on sheath. Cone apex rounded to apiculate with blunt tip; spores green, spheric. 2 n =216.
"Stems all alike, annual (reputedly sometimes perennial toward the southwest), mostly unbranched, 3–10 dm, 3–8 mm thick, with mostly (10–)16–32 ridges, these smooth or commonly with inconspicuous, low, transverse wrinkle-ridges; central cavity mostly 2/3–3/4 the diameter of the stem, much larger than the small vallecular ones; stomates in 2 lines in each furrow; sheaths mostly 7–15 mm, mainly green, black-banded at the apex only, or the lowest ones sometimes black also at the base or throughout, the dark, scarious-margined teeth promptly and regularly deciduous; cones short-pedunculate, 1–2.5 cm, blunt or often inconspicuously short-apiculate. Open wet places; s. B.C. to Baja Calif., e. to s. Ont., w. N.Y., O., w. Va., Ill., Okla., and Tex. (E. kansanum)"
|Smooth scouring rush|