Carex media is a tufted perennial sedge that occurs widely in Denali in forests, shrublands, and meadows, frequently on floodplains and stream terraces. This species has a single scabrous culm 15-50 cm tall, arising from a short rhizome. The leaves are shorter than the stem, 2-4 mm wide, with inrolled margins and reddish to brown sheaths. The lowest bract is leaf-like and more or less equal in length to the inflorescence. The terminal spike is bisexual with the female flowers above, male flowers below. Lateral spikes contain only female flowers. The spikes (2-5) are globose, two-colored (green/purple-black), aggregated, and short-stalked. The pistillate scales are brown with light green, transparent margins, lanceolate to ovate in shape and shorter than the perigynia. Perigynia are green (aging to brown), papillose, and elliptic in shape, 2.5-3 mm long. The fruits are achenes with 3 stigmas. Similar species in Denali include C. atrosquama, in that species the pistillate scales lack a transparent margin, and the spikes and perigynia are larger.
Carex media is perennial and flowers around mid-summer (July).
C. media is monoecious, but male and female flowers are produced in separate spikes. Species in the genus Carex are wind pollinated, but usually also self-pollinate to some degree (Bertin 2007; Friedman and Barrett 2009). Seeds are gravity and water dispersed.
Carex media is an incompletely circumpolar species (circumboreal) with a boreal-montane distribution, ranging widely across northern Eurasia to North America, but absent from Greenland. In North America, this species occurs from Alaska eastward across Canada to Labrador and southward into Maine, Minnesota, Michigan, Wisconsin, Montana, Washington and Oregon. In Alaska, C. media occurs scattered in suitable habitat statewide, except is apparently rare on the Arctic slope, Aleutians, and southeast panhandle. In Denali, this species occurs occasionally park wide in suitable habitat on both sides of the Alaska Range.
C.media is observed in the park at elevations ranging from 164 m to 992 m with an average site elevation of 454 m. It is generally found on flat sites, with an average slope angle of 2 degrees. When it is found on steeper slopes, it is found slightly more on south-facing slopes.