Elymus trachycaulus is a perennial, tufted grass with narrow spikes of sessile spikelets found in disturbed situations across Denali gravel bars, rocky areas, and sloping meadows. Plants grow 0.4-1 m tall from fibrous roots. Leaves are flat, 2-5 mm wide, alternate. Ligules are membranous, 0.2-0.8 mm wide. The inflorescence is a spike, 8-25 cm long, with one spikelet per rachis node. Spikelets have 3-9 bisexual flowers. The glumes are shorter than the included florets and about 3/4 the length of the lemmas, the second glume slightly longer than the first, with awns 11-17 mm long. The lemmas are awnless or with awns up to 5 mm long. Lemmas are hairless to short hairy. The fruit is single-seeded, indehiscent and dry. Some key features for identifying this species include the sessile spikelets, short-awnedlemmas, the glumes 3/4 as long as the lemmas and the one spikelet per rachis node, but there are many closely related species and subspecies, and those wishing to make an identification in confidence should consult a technical key.
Elymus trachycaulus flowers in mid to late summer and produces seed in the fall.
This species is monoecious. It is predominately self-pollinated and produces seed in abundance (Heath et al. 1985), but can be pollinated by wind. Seeds are dispersed by hooking onto animal fur and clothing. Seeds are viable for 3-6 years, and requiring 1-2 months of short-night stratification to germinate (Howard 1992). Seeds are the primary dispersal agent, but plant can produce side shoots (tillers) and spread vegetatively.
Elymus trachycaulus is a North American species. It is found across the continent, the southern range limits in Texas and Kentucky, reaching north to Alaska, Yukon, Northwest Territories, and Greenland. This species is not found in the Canadian high arctic. In Alaska, it occurs from Southeast to the Brooks Range, extending west to the Alaska Peninsula and Seward Peninsula, but not reaching the Aleutian Islands. In Denali, it occurs in suitable habitats on both sides of the Alaska Range.
Elymus trachycaulus is primarily an alpine species in Denali, most abundant at 900-1100 meters, but there are handful of occurrences at low elevations as well. This species shows a marked preference for steep slopes, occurring in 11% of plots above 28 degrees slope. It occurs on all aspects, but is most frequent on east or west facing slopes.