Plants perennial; rhizomatous. Culms 10-150 cm, erect, glabrous. Sheaths usually closed for up to 1/5 of their length; ligules membranous, obtuse, erose or lacerate; blades usually flat, glabrous, often scabrous. Inflorescences terminal panicles, loose and open to narrow and contracted; branches 0.5-14+ cm, scaberulous. Spikelets 3-6.5 mm, pedicellate, laterally compressed, with 1 (rarely 2) floret(s); rachillas hairy or scabrous, sometimes prolonged beyond the single floret or terminating in a well-formed or vestigial floret; disarticulation above the glumes. Glumes shorter than the lemmas, or the upper glumes equal to the lemmas, ovate to lanceolate, glabrous, sometimes scabridulous, 1-3-veined, acute to obtuse; calluses weakly developed, glabrous; lemmas scabrous or puberulent, 3-5-veined, lateral veins sometimes obscure, not reaching the apices, apices obtuse to acute, sometimes mucronate, unawned; paleas about as long as the lemmas, folded along 1 prominent vein, the second vein faint; lodicules 2, glabrous; ovaries glabrous; anthers 3. Caryopses 1.7-3 mm; hila 1/4-1/3 the length of the grain. x = 7. Name from the Greek arktos, north, a reference to the distribution of the genus, and Agrostis, from its similarity to that genus.