Culms 30-150 cm. Spikes (4)8-30 cm long, 0.5-0.8 cm wide, 2-sided; internodes 8-15 mm. Spikelets with 3-9 florets, the bases usually visible. Glumes 5-17 mm, at least 1 vein scabrous to near the base, sometimes all veins scabrous, unawned or with straight awns shorter than 2 mm; lemmas unawned or awned, awns to 5 mm, straight.
Elymus trachycaulus subsp. trachycaulus grows throughout the habitat and range of the species, and exhibits considerably more variation than subsp. subsecundus . Two aspects of the variation that seem particularly worthy of further study are the glume venation, and the spacing of spikelets in the spikes. Plants with glumes having 5-7 well-developed, narrowly spaced veins are restricted to lower elevations and the southern portion of the subspecies range; northern plants and plants at higher elevations generally have 3-5 weakly developed and widely spaced veins. The former glumes resemble those of E. glaucus , with which E. trachycaulus subsp. trachycaulus is often sympatric; the latter, those of E. violaceus . Spikelet spacing also varies considerably. In at least some instances, plants with widely spaced spikelets appear to be associated with more shady habitats.