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..
Glabrous, culms 1°-2° tall, erect, slender, branched, smooth. Sheaths shorter than the internodes, ligule short, ciliate; blades 2'-6' long, 1" wide or less, flat, attenuate into a long point, smooth or scabrous; panicle 3'-7' long, at first strict, the branches finally more or less spreading; first scale of spikelet 1-nerved, or occasionally with an obscure additional nerve on each side, shorter than the second scale; third scale equalling or longer than the second; awns divergent, the middle one 4"-8" long, the lateral ones shorter.
Culms densely tufted, 6'-10' tall, erect, rigid, simple; leaves confined to the base of the culm; sheaths with a tuft of hairs on each side at the apex; blades involute, often curved, 1/4" in diameter, those on the culm usually 2, up to 2' long, the basal ones longer; panicle 3'-4' long, strict, its branches short and appressed and usually bearing but a single spikelet; spikelets 6"-7 1/2" long, the 2 outer scales 1-nerved, the first scale about i as long as the second, the flowering scale 41/2"-6" long, equalling or a little shorter than the second scale, the awns ascending, the central one l'-2' long, the lateral awns a little shorter.
In dry sandy soil, South Dakota to Utah, Texas and New Mexico. Figured in our first edition for A. purpurea Nutt., which has not as yet been detected within our limits.
Culms tufted, 1°-2° tall, simple, leafy; blades involute, those on the culm usually 3 or 4, 1'-8' long, often curved, as are the commonly longer basal ones; panicle 4'-8' long, its branches more or less spreading, the longer usually bearing 2-4 spikelets; spikelets 6"-71/2" long, the 2 outer scales i-nerved, the first scale about 1/2 as long as the second, the flowering scale 5"-6" long, usually a little shorter than the second scale, the awns ascending, the central one 1'-1 1/4' long, the lateral awns a little shorter.
In dry sandy soil, Kansas to Texas and New Mexico. July, Aug.
A. longiseta Steud. Syn. Gram. 420. 1855.
Culms tufted, 8-16' tall, simple; blades 1'-4' long, involute; panicle 4-8' long, its branches usually ascending, bearing generally 1 spikelet, or in the longer branches sometimes 2 spikelets; spikelets 10"-12 1/2" long, the 2 outer scales 1-nerved, the first one about i as long as the second, the flowering scale 6"-8" long, occasionally a little shorter, from a little over i to § as long as the second scale, the awns ascending, the central one 2 1/2'-4 1/2' long, the lateral ones equalling it or a little shorter.
In dry sandy soil, Montana and Washington to Nebraska, Texas and Mexico. July, Aug.