Carex millegrana T. Holm; C. stricta Lamarck var. elongata (Boeckeler) Gleason; C. stricta var. emoryi (Dewey) L. H. Bailey; C. variabilis L. H. Bailey var. elatior L. H. Bailey; C. virginiana Woods var. elongata Boeckeler

Plants not cespitose. Culms acutely or obtusely angled, 30–115 cm, scabrous. Leaves: basal sheaths red-brown; sheaths of proximal leaves glabrous, fronts lacking spots and veins, apex convex, prolonged; blades 3–6 mm wide. Inflorescences: proximal bract equal to inflorescence, 3–5 mm wide. Spikes erect; proximal 3–5 spikes pistillate, 2.5–10 cm × 3–5 mm, base attenuate; terminal 2–3 spikes staminate. Pistillate scales pale or red-brown, equaling perigynia, apex acute, awnless. Perigynia ascending, green, spots absent, 3–5-veined on each face, somewhat flattened, loosely enclosing achenes, ellipsoid, 1.7–3.2 × 1–2.1 mm, dull, apex rounded or obtuse, papillose; beak 0.1–0.3 mm. Achenes not constricted, dull. 2n = 72.

Fruiting May–Jun. Stream banks, ditches, seeps; 0–1200 m; Man., Ont.; Ark., Colo., Conn., Del., D.C., Ill., Ind., Iowa, Kans., Md., Mich., Minn., Mo., Nebr., N.J., N.Mex., N.Y., N.Dak., Ohio, Okla., Pa., S.Dak., Tex., Va., W.Va., Wis., Wyo.; Mexico (Chihuahua, Coahuila).

Carex emoryi resembles C. aquatilis in size and habit, and has similar sheaths and spike dimensions. It is distinguished by the finely veined perigynia, the prolonged convex sheath apex and truncate ligule, and the hypostomic leaves. Most specimens identified as C. aquatilis var. altior are C. aquatilis; the type of C. aquatilis var. altior is an immature specimen of C. emoryi. Although previously thought to be related to C. stricta, the differences in sheath characters and higher chromosome number suggest that C. emoryi is not a member of the C. stricta subgroup.