Plants densely cespitose, without rhizomes. Culms (25)50–80(105) cm, erect, glabrous and smooth throughout. Sheaths closed for about 1/2 their length, glabrous, smooth, usually reddish blue towards the bases, persistent, flag leaf sheaths tightly enclosing the culms; collars glabrous; ligules 0.1–0.5 mm; blades 0.6–1.2(1.5) mm in diameter, conduplicate, abaxial surfaces glabrous, smooth or scabrous, adaxial surfaces scabrous, veins (5)7–9, ribs 5–9; abaxial sclerenchyma in (5)7–9 broad strands, rarely some strands confluent; adaxial sclerenchyma absent. Inflorescences (3)8–18 (25) cm, open or loosely contracted, with 1–2(3) branches per node; branches somewhat lax, erect to spreading, lower branches with 2+ spikelets. Spikelets (5)6–8.5(10) mm, with (3)4–6(8) florets. Glumes exceeded by the upper florets, lanceolate, mostly smooth and glabrous, sometimes scabrous distally; lower glumes 2.5–4 mm; upper glumes 3–5(5.5) mm; lemmas (3.5)4–5.6(6.6) mm, usually smooth, sometimes scabrous near the apices, lanceolate, usually acute, sometimes obtuse, unawned, occasionally mucronate; paleas about as long as the lemmas, intercostal region smooth or slightly scabrous distally; anthers (2)3–4 mm; ovary apices glabrous or sparsely pubescent. 2n = 14.
Festuca amethystina is sometimes cultivated as an ornamental species; it may occasionally escape.