General: Perennial grass from scaly rhizomes; stems hollow, erect, often branched above, minutely rough below the nodes, 30-90 cm tall.
Leaves: Sheaths smooth to minutely rough, sometimes appressed-hairy below the nodes, slightly keeled; blades flat, 2-20 cm long, 2-6 mm wide, smooth to hairy below, the nerves very unequal in prominence; ligules membranous, jagged and more or less fringed with fine hairs, squared-off at the tips, 0.4-1 mm long.
Flowers: Inflorescence a narrow, spikelike, congested, densely flowered panicle, 2-21 cm long, 0.3-2.4 (3) cm wide, the several branches 0.3-5.5 cm long, closely appressed or slightly spreading (up to 30degree from stem axis), with secondary panicles often arising from the upper nodes; spikelets densely clustered, 1-flowered, nearly unstalked to short-stalked, often purple-tinged; glumes very narrow, 1-nerved, more or less hairy below on the keels, usually minutely short-hairy, nearly equal, (1.5) 1.8-3.7 (4) mm long, equal or slightly shorter than the lemmas, the tips long-pointed to awn-tipped, when present, the awns up to 2 mm long; lemmas lanceolate, soft-hairy below, minutely rough, short soft-hairy along the midnerves and margins on the lower half, 1.5-3.8 mm long, the tips long-pointed, unawned or awned, the awns up to 10 mm long, the calluses short soft-hairy, the hairs less than 1.5 mm long; paleas narrowly lanceolate, 1.5-3.8 mm long, the tips long-pointed; anthers 0.3-0.5 mm long, yellow to purplish.
Wet, moist or mesic slopes, road embankments, ditches, lake margins, hot springs, meadows, and waste areas near railroad tracks in the lowland, steppe and montane zones; infrequent in SW and E BC; N to YT, E to NS and NB and S to ME, PA, NC, AL, AR, TX, NM, AZ and CA.
