Plants densely cespitose. Culms dark maroon at base; flowering stems 25–60 cm, usually longer than leaves at maturity, 0.5–0.7 mm thick, glabrous or sparsely pubescent, finely scabrous within inflorescence. Leaves: basal sheaths maroon, bladeless, pubescent; others grading from maroon to green on back, pale brown-hyaline, red dotted and usually pubescent on front; blades flat, 1.5–3 mm wide, glabrous or sparsely pubescent on both surfaces, especially near sheath, finely scabrous on margins. Inflorescences: peduncles of lateraal spikes 5–25 mm, shorter than spikes, glabrous; peduncle of terminal spike 5–25 mm, glabrous; proximal bracts often equaling or exceeding inflorescences; sheaths to 9 mm; blades 1–2 mm wide. Lateral spikes 2–4, 1 per node, well separated, erect or arching, pistillate with 15–30 perigynia attached 1 mm apart distally and 3 mm apart proximally, linear, 15–50 × 3–3.5 mm. Terminal spike gynecandrous, 20–35 × 1.5–3.5 mm. Pistillate scales pale hyaline, tinged with golden or reddish brown, with broad green midrib, red dotted, oblong-elliptic, shorter than mature perigynia, apex obtuse to cuspidate, glabrous. Perigynia green, copiously red dotted, 2-ribbed and finely 12–15-veined, loosely enveloping achene, ovoid-ellipsoid, 2–3.2 × 0.8–1 mm, membranous, base with short stipe, gradually tapering to acute beakless apex, glabrous. Achenes distinctly stipitate, 1.8–2.1 × 0.8–1 mm, stipe 0.5 mm. 2n = 56.
Phenology: Fruiting summer.
Habitat: Dry to mesic forests, seepage slopes, and meadows in the mountains
Elevation: 0–1600 m
Ala., Ga., Ky., Md., N.Y., N.C., Pa., S.C., Tenn., Vt., Va., W.Va.
Variants of Carex aestivalis with larger perigynia have been collected from Virginia and North Carolina. Carex aestivalis apparently hybridizes with C. gracillima and C. virescens.