Poa arctica is a common, highly variable rhizomatous perennial grass that occurs widely across Denali from the lowlands to high alpine areas. This species occurs in a variety of habitats from muskeg to sparsely vegetated alpine slopes. Plants are usually rhizomatous with erect stems, 10-30 cm tall usually with 2 nodes along the stem. Leaves are mostly basal, short, often narrow and thin; flat to involute in cross-section. The ligules are membranous. The inflorescence is an open pyramidal panicle, the branches often flexuose. Spikelets mainly have two bisexual flowers. The two glumes are of equal length. The lemmas are long-hairy between the nerves and have a basal tuft of cobwebby hairs present. Paleas are hairy. Anthers are longer than 1 mm. Fruits are single-seeded, indehiscent and dry. The long-hairy lemma helps to distinguish this species from other Poa species in the park.
Poa arctica is perennial and flowers mid-summer in Denali.
Poa arctica is monoecious, with stamens and pistils in the same florets (bisexual). Flowers are wind pollinated. Seeds are gravity and wind dispersed. viviparous plants are sometimes encountered.
Poa arctica is a widespread and highly variable species complex with complex taxonomy and numerous subspecies. In the broad sense, Poa arctica has a circumpolar worldwide distribution. In North America, it ranges from Alaska, into all Canadian provinces, and south through the Rocky Mountain states to New Mexico, and west to Washington state. This species is common and widespread throughout Alaska. In Denali, it occurs widely in numerous habitats on both sides of the Alaska Range crest.
Poa arctica is primarily an alpine species that grows from 134 m to 1742 m, with an average plot elevation of 1000 m. It does not show a strong affinity towards any aspect. It is commonly found on moderate to steep sites, with an average plot slope of 15 degrees.