Equisetum laevigatum A.Braun

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)

It is a temperate plant.

CAUTION: The rootstocks are dried and used for food.