Plants medium-sized. Rhizome erect or creeping, blackish brown, nodes and roots with sparse long yellowish brown trichomes or glabrous. Aerial stem annual, dimorphic, fertile and sterile stems appearing simultaneously. Fertile stems straw-colored, 15-25 cm tall, 2-2.5 mm in diam. at middle, branched eventually, 10-14-ridged; ridges glabrous; sheath tubes grayish green, ca. 0.6 cm; internodes 2-3 cm; sheath teeth 10-14, light brown, lanceolate, 4-6 mm, membranous, with shallow grooves abaxially. Fertile stems remaining alive after spores shed. Sterile stems straw-colored or grayish green, 30-60 cm, 2-2.5 mm in diam. at middle, well branched in whorls, unbranched below middle, main stem 14-22-ridged; ridges arc-shaped abaxially, each ridge often with a row of tubercles; internodes 2.2-2.8 cm; sheath tubes long, narrow, ca. 3 mm, lower portion grayish green, upper portion grayish green but with a light brown band; sheath abaxially 2-ridged; sheath teeth 14-22, light brown but with a blackish brown line, lanceolate, membranous, persistent. Lateral branches slender, complanate, with 3 or 4 narrow and tall ridges; ridges glabrous abaxially; sheath teeth not open. Strobilus ellipsoid-terete, 1-2.2 cm, 3-7 mm in diam., apex blunt; stalk prolonged when mature and 1.7-4.5 cm. 2n = 216.
Aerial stems dimorphic; vegetative stems green, branched, 16--50 cm; hollow center 1/6--1/3 stem diam. Sheaths somewhat elongate, 3--5 × 2--4 mm; teeth 8--18, narrow, 1.5--4 mm, centers dark and margins white. Branches in regular whorls, horizontal to drooping, solid; ridges 3; valleys channeled; 1st internode of each branch equal to or longer than subtending stem sheath; sheath teeth deltate. Fertile stems brown, with stomates, initially unbranched, persisting and becoming branched and green after spore discharge.
"Stems annual, dimorphic, the sterile ones 2–5 dm, 1–3 mm thick, smoothish toward the base, otherwise beset with high, blunt, siliceous tubercles or very short, high, transverse ridge-crests on the (6–)10–18 ridges, with rather small vallecular cavities and a fairly large central cavity commonly 1/3–1/2 the diameter of the stem, the stomates in 2 broad bands in each furrow; sheaths 2–6 cm, green, the teeth 1–2 mm, persistent, only basally connate, with pale, hyaline margins and a firmer dark midstripe; branches regularly whorled at the middle and upper nodes, solid, mostly 3-angled, simple, the first internode to as long as the associated stem-sheath; fertile stems with simple branches, otherwise as in E. sylvaticum. Streambanks and moist woods; circumboreal, s. in our range to N.J. and ne. Io."
|Meadow horsetail, prêle des prés|