Plants densely cespitose, with-out rhizomes. Culms 18–40(60) cm, mostly scabrous or pub-erulent below the inflorescence. Sheaths closed for less than 1/3 their length, smooth or scab-rous, glabrous or finely pub-erulent, persistent; collars glabrous; ligules 0.1–0.4 mm; blades 0.2–0.4(0.6) mm in diameter, conduplicate, abaxial surfaces smooth, adaxial surfaces scabrous, veins 5(7), ribs 1, distinct; abaxial sclerenchyma forming a continuous or almost continuous band; adaxial sclerenchyma absent. Inflorescences 1–6(14) cm, usually contracted, with 1–2 branches per node; branches usually erect, lower branches with 2+ spikelets. Spikelets 3–6(6.5) mm, with 2–6(8) florets. Glumes exceeded by the upper florets, ovate-lanceolate to lanceolate, glabrous; lower glumes 1–2.5 mm; upper glumes (1.7)2–3(3.9) mm; lemmas 2.3–4(4.4) mm, obtuse to acute, mostly smooth and glabrous, sometimes scabrous or pubescent distally, unawned, sometimes mucronate, mucros to 0.4 mm; paleas about as long as the lemmas, intercostal region smooth or scabrous distally; anthers (1)1.5–2.2 mm; ovary apices glabrous. 2n = 14 (28).
Festuca filiformis is a European species that has been introduced to the Flora region as a turf grass. It grows well on poor, dry soils and is becoming a ruderal weed in some areas. It is particularly common in the northeastern United States and southeastern Canada, but has been reported from scattered locations elsewhere.