Culms 50-130 cm. Ligules 1-3 (4.6) mm, truncate to obtuse, ciliolate; blades 15-80 cm long, 4-8 mm wide when flat, usually involute, 0.5-2.5 mm in diameter when involute; flag leaf blades 5-39 cm. Panicles 9-40 cm long, 10-25 mm wide, stramineous. Glumes 8-15 mm, exceeding the florets; callus hairs 1-3 mm; lemmas 8-11.5(14) mm, somewhat thicker than the glumes, apices acute, entire, unawned, rarely mucronate, mucros to 0.2 mm, subterminal; anthers 3-7 mm.
Conn., N.J., N.Y., Wash., Va., Del., Wis., N.H., N.C., Pa., R.I., B.C., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Mass., Maine, Vt., Calif., Ill., Ind., Md., Ohio, Minn., Mich., S.C., Oreg.
The two subspecies overlap in their morphological characteristics and occupy similar habitats, the primary difference between them being their flowering time.