Rhizomes elongate, covered with shiny, coriaceous, scalelike leaves. Culms to 2.4 m. Sheaths glabrous to densely pubescent; ligules 0.7-2.5 mm; blades to 64 cm long, about 12 mm wide. Panicles 15-78 cm long, 1.7-26.4 cm wide; branches to 33 cm, erect to strongly divergent, lowermost branches sometimes reflexed. Spikelets 5-8.5 mm. Glumes straight; lower glumes 3.5-6.5 mm; upper glumes 5-8.2 mm; lemmas 4.5-7.1 mm, straight, glabrous; paleas 4.4-6.9 mm, glabrous. 2n = 40, ca. 60.
Ill., Ind., Colo., N.Mex., Wash., Mont., Alta., B.C., Man., Ont., Sask., Minn., Mich., Iowa, Idaho, Kans., Mo., N.Dak., Nebr., Pa., S.Dak., Wyo., Wis., N.Y., Ohio
Calamovilfa longifolia usually grows in sand or sandy soils, but is occasionally found in clay soils or loess. Two geographically contiguous varieties exist. They differ as shown in the following key; the differences between the two are more striking in the field.
"decumbent" is not a number.