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..
Hordeum jubatum L. Sp. PI. 85. 1753.
Culms 10'-2 1/2° tall, erect, simple, usually slender, smooth and glabrous. Sheaths usually shorter than the internodes, generally loose, smooth and glabrous; ligule 1/2" long or less; blades 1'-5' long, 1"-2" wide, erect, rough; spike 2'-4' in length; spikelets usually in 3's, the central one containing a palet and perfect flower, the lateral imperfect; empty scales consisting of slender rough awns l'-2 1/2' long; flowering scale of the central spikelet 3"-4" long, scabrous at the apex, bearing a slender rough awn 1'-21/2' long; the corresponding scale in the lateral spikelets short-awncd, about 3" long including its pedicel, sometimes reduced to a rudiment.
In dry soil, Ontario to Alaska, south to Illinois, Texas and California. Naturalized in the east from Labrador and Quebec to New Jersey and Pennsylvania. July-Aug.
Hordeum murinum L. Sp. PI. 85. 1753.
Culms 6'-2° tall, erect, or decumbent at the base, smooth and glabrous. Sheaths loose, shorter than the internodes on the long culms, overlapping on the short ones, the uppermost often inflated and enclosing the base of the spike; ligule very short; blades 1'-6' long, 1"-3" wide, rough; spikes 2'-4' in length; spikelets usually in 3's; scales awned, the empty ones awn-like, scabrous, those of the central spikelet broader and ciliate on the margins, bearing awns 9"-12" long, those of the lateral spikelets similar, with the exception of the second scale, which is not ciliate; flowering scales scabrous at the apex, bearing an awn about 1' long, those of the lateral spikelets about 6" long, the corresponding scale in the central spikelet somewhat smaller.
On ballast and sparingly in waste places, Massachusetts to District of Columbia. Also from Arizona to Utah, California and British Columbia. Adventive or naturalized from Europe. Wild- or Mouse-barley. Squirrel-tail. June-July.
Perennial. Culms 2°-3° tall; leaves glabrous; sheaths smooth, shorter than the internodes; blades 4'-8' long, 2"-4" wide, rough; spikes 3'-6' long, 10"-15" in diameter; lateral spikelets nearly sessile, each with a perfect flower, the central spikelet with 2 perfect flowers, the empty scales subulate, long-awned, the flowering scales lanceo-lute, about 3' long, exclusive of the awn, which is two to three times their length.
On prairies, Illinois to South Dakota and Wyoming. July and Aug.