Mary E. Barkworth, Julian J.N. Campbell and Bjorn Salomon
Plants densely cespitose, shortly rhizomatous. Blades (2)4–8(15) mm wide, abaxial surfaces scabrous, adaxial surfaces pilose. Spikes 14–30 cm long, 1–2.5 cm wide including the awns, 0.3–0.8(1.5) cm wide excluding the awns, drooping, with 1–2 spikelets per node; internodes 5–20 mm, scabrous on the angles. Spikelets with 3–9 florets. Glumes 4–10.5 mm long, 0.8–1.5 mm wide, oblong to lanceolate, scabrous, gradually or abruptly narrowing in the distal 1/3–1/4, 3(4)-veined, margins scarious, apices unawned or awned, awns to 15 mm; rachillas hairy; lemmas 8.5–15 mm, hairy, conspicuously keeled distally, awned, awns 3–10 mm; paleas 8.5–15 mm, retuse or truncate; anthers 1–2 mm.
Elymus ×palmerensis is the name for hybrids between Elymus macrourus and E. sibiricus . It is known from disturbed sites around Palmer, Alaska, and in southcentral Alaska. Bowden (1967) also reported it from Fort Liard, in the MacKenzie District, Northwest Territories. Lepage (1952) originally identified the parents as Agropyron sericeum [= Elymus macrourus] and E. canadensis . Later, Lepage (1965) stated that the second parent was E. sibiricus. The above description includes ×Agroelymus hodgsonii Lepage , which, according to Bowden (1967), is a synonym.