Carex canescens is a loosely to densely tufted sedge of wetland habitats including wet bogs, pond margins, beaver impoundments, and fens, with several tightly clustered yellow-green spikes of flowers. Stems grow 10-50 cm tall, erect, from short rhizomes. The leaves are shorter than the stem, flat, soft, 2-4 mm wide, glaucous green in color. Plants lack a subtendingbract. Male and female flowers are produced in the same spike, the pistillate flowers above the male. The inflorescence consists of 4-8 spikes, all sessile. The uppermost spikelets are bunched together, the lower more widely space. The pistillate scales are translucent, whitish, and ovate. The perigynia are ovoid and gradually tapering to a beak with scabrous margins, light green to straw colored, becoming brown, the nerves not prominent. The fruits are achenes, with abrupt beaks. Carex brunnescens and Carex lapponica superficially look very similar. Carex brunnescens has two-beaked perigynia, Carex lapponica is not tufted, and the perigynia beak is smooth.
Carex canescens flowers and fruits from June to August.
Carex canescens is monoecious, but male and female organs are produced in separate flowers, in the same spike. Species in the genus Carex are wind pollinated, but usually also self-pollinate to some degree (Bertin 2007; Friedman and Barrett 2009). Seeds are wind and water dispersed.
Carex canescensis a circumpolar wetland species with a boreal-montane distribution. In North America, C. canescens is widespread, occurring in Alaska and across Canada, south to New England, the mid-Atlantic states, the upper Midwestern states and across all of the western continental U.S. including the Southwest. In Alaska, this species occurs scattered in suitable habitat from the Brooks Range southwards. In Denali, C. canescens is similarly widespread in boreal regions on both sides of the Alaska Range.