Plants rhizomatous, densely cespitose. Culms 20–30 cm. Sheaths reddish brown, glabrous or pubescent, shredding into fibers, cauline leaf sheaths loosely or tightly enclosing the culms; blades 0.7–1.5 mm in diameter, conduplicate; abaxial sclerenchyma in narrow strands; adaxial sclerenchymasometimes present. Inflorescences mostly congested, lanceolate, often partially included in the uppermost leaf sheaths at maturity; branches scabrous. Spikelets to about 12 mm, with 4–8 florets. Lower glumes 2.5–3.2 mm; upper glumes 3.5–4.6(5) mm; lemmas 4.5–6 mm, glabrous or pilose, acuminate in side view, apices awned, awns 0.5–2 mm; anthers 2.5–3 mm long. 2n = 42 [for Festuca rubra var. littoralis Vasey ex Beal].
Festuca rubra subsp. mediana grows in sand beaches and dunes along exposed coasts, from Vancouver Island to Oregon.