Aerial stems monomorphic, green, branched or occasionally unbranched, 2--70 cm; hollow center 2/3--4/5 stem diam. Sheaths somewhat elongate, 3.5--8 × 2.5--6 mm; teeth dark, 7--14, narrow, 1--3 mm. Branches mostly from midstem nodes, ascending to spreading, solid; ridges 4--5; valleys channeled; proximal whorls with 1st internode of each branch equal to subtending stem sheath, distal whorls with 1st internode of each branch longer than stem sheath; sheath teeth attenuate. Cones maturing in early summer, but misshapen spores not shed. Ditches, stream banks, wet meadows; 0--1000 m; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Conn., Del., Idaho, Ill., Ind., Iowa, Maine, Md., Mass., Mich., Minn., Mont., Nebr., N.H., N.J., N.Y., N.Dak., Ohio, Oreg., Pa., R.I., S.Dak., Vt., Va., Wash., W.Va., Wis., Wyo. Equisetum × litorale is a hybrid between E . arvense and E . fluviatile . It should be expected where the parents coexist. This hybrid has been mistaken for Equisetum palustre ; the solid branches with long first internodes and channeled valleys distinguish it from that species.
