Leymus innovatus is a rhizomatous grass with distinctive large, fuzzy flowering heads that occurs widely in Denali, most commonly in floodplains and terraces in or near the mountains on the north side of the Alaska Range crest. Plants grow 30-100 cm tall from a creeping rhizome, but often forms clumps. Leaves are mostly basal, 2-6 mm wide, stiff and involute. The ligules are membranous. The stem leaves are short, 2-5 mm wide and hairless. The inflorescence is a purplish spike, with two spikelets per node. The flowers are reduced into a series of bracts (florets) where each spikelet consists of 2-3 bisexual florets where one is often undeveloped. The glumes are unequal lengths, broadest at base. The lemma is longer than glume with an attached short awn, 2-4 mm long. The anthers are purple. The fruit is single-seeded, indehiscent and dry. Similar grasses in Denali include species of the genus Elymus, which have soft leaves (not stiff) and the glumes are broader above the base.
Boreal wildrye begins to green in March and April. It flowers in June and July and has been reported to remain in flower until early September.
Plants are monoecious with bisexual florets.Florets are wind pollinated. Seeds are wind dispersed. Plants also spread asexually via rhizomes.
Animals do eat this grass but not very often due to it being unpalatable.
Leymus innovatus is endemic to North America, where it occurs in Alaska, southwards through western Canada to the upper Great Plains, northern Rockies, Pacific Northwest, and in Canada reaching eastwards to Ontario. In Alaska, L. innovatus is arctic-alpine occurring primarily in the Brooks and Alaska Ranges, with isolated localities on the North Slope. In Denali, this species occurs primarily north of the Alaska Range, and in localities clustered in the upper Chulitna and Yentna river drainages, extending into adjacent boreal lowlands along major river corridors.