This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial tufted grasses, with usually involute leaves and a contracted or open panicle. Spikelets 1-flowered. Scales 3; outer 2 membranous, glabrous; third scale firmer, becoming hard in fruit, densely pubescent with long silky hairs, and bearing a terminal readily deciduous awn, the callus at the base of the scale short and obtuse. Stamens 3. Stigmas plumose. Grain free, enclosed in the scale. [Greek, referring to the copious silky hairs of the flowering scale.]
Dept. Agric. 63: 23. 1883. O. membranacea Vasey, Grasses S. W. Part 2, pl. 10. 1891.
Culms glabrous, 1 °-2° tall, erect, rigid, simple, smooth. Sheaths usually shorter than the internodes, smooth or somewhat rough; ligule 1"-2" long, acute; leaves 6'-12' long, less than 1" wide, involute, stiff, smooth or somewhat scabrous; panicle 6'-1° long, diffuse, generally partially included in the upper sheath, its branches widely spreading and many times forked, the ultimate divisions flexuous; outer scales of the spikelet 3"-4" in length, long-acuminate, glabrous; third scale about one-half as long, acute, densely pubescent with long silky erect hairs nearly twice its own length, the awn 2"-3" long. On prairies, Saskatchewan to Washington, Iowa, Texas and Mexico. Bunch-grass. May-July.