Carex microchaeta is a tufted perennial sedge that is the most common and abundant sedge of alpine tundra in Denali, especially north of the Alaska Range crest. This attractive alpine sedge has wide basal leaves and an erect stem 5-35 cm tall arising from a stout horizontal rhizome. Leaves are all basal, flat or V-shaped, green, 3-6mm wide and shorter than the stem. The lowest bract is leaf- or scale-like and shorter than the inflorescence. Plants produce male and female flowers in separate spikes. The inflorescence consists of 1-2 terminal staminatespikes and 1-3 lateral drooping pistillatespikes on long peduncles. The pistillate scales are reddish-brown to purple with a light colored mid-rib that tapers to a short acute point. Perigynia are brown to blackish, papillose and typically concealed by the scales. Fruits are 3-angled achenes with 3 stigmas. A similar sedge is Carex podocarpa, but that plant has stem leaves, not basal leaves.
Carex microchaeta is perennial and flowers in mid-summer (July).
Carex microchaeta 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 most likely wind disseminated.
Carex microchaeta is an amphi-Beringian species with an arctic-alpine distribution. This sedge occurs across mountainous and arctic regions of Alaska and into northwestern Canada, including Yukon, Northwest Territories and British Columbia. In Denali, C. microchaeta occurs in alpine areas throughout the park on both sides of the Alaska Range, although it is most common in tundra on the north side.
Carex microchaeta is primarily an alpine species commonly occurring in Denali from 614 m to 1787 m, with an average plot elevation of 1131 m. This species most frequently occurs in plots with an elevation over 1100 m. This species shows a strong preference to steeper plots with an average plot slope of 18 degrees. C. microchaeta slightly prefers north facing slopes.