Plants densely cespitose, with-out rhizomes. Culms 10–37 cm, erect, glabrous, smooth. Sheaths closed for about 1/2 their length, glabrous, per-sistent; collars glabrous; ligules 0.2–0.5 mm; blades 0.4–0.7(1) mm in diameter, conduplicate, veins 5–7, ribs 1–5, abaxial surfaces smooth, adaxial surfaces scabrous or puberulent; abaxial sclerenchyma in 5–7 strands, at least twice as wide as high, often some strands confluent; adaxial sclerenchyma absent. Flag leaf sheaths tight or somewhat loose; flag leaf blades 1–5 cm. Inflorescences (1.5)2–5 cm, contracted, with 1–2 branches per node; branches erect, lower branches with 2+ spikelets. Spikelets 4–5.6(6) mm, with 3–4(5) florets. Glumes exceeded by the upper florets, ovate-lanceolate, mostly glabrous and smooth, sometimes scabrous distally; lower glumes 1.5–2 mm, lanceolate to ovate-lanceolate; upper glumes (2)2.2–2.7 mm, ovate; lemmas (2.5)3–3.5(4) mm, ovate-lanceolate to lanceolate, usually scabrous distally, sometimes smooth, usually awned, occasionally unawned, awns 0.7–2.1 mm, terminal; paleas about as long as the lemmas, intercostal region smooth or scabrous distally; anthers 0.8–1.3 mm; ovary apices glabrous. 2n = 42.
Festuca groenlandica is endemic to Greenland. Scholander (1934) initially described it as a variety of F. brachyphylla, but it differs from that species in having more extensive blade sclerenchyma, usually 7 broad abaxial strands rather than 5 narrow strands.