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..
Bromus tectorum L. Sp. PI. 77. 1753.
Culms 6'-2° tall, erect from an annual root, simple, smooth and glabrous. Sheaths usually longer than the internodes, at least the lower ones softly pubescent; ligule 1"-2" long; blades 1'-4' long, 1"-2" wide, softly pubescent; panicle 2'-6' in length, open, the branches slender and drooping, somewhat one-sided; spikelets numerous, 5-8-flowered, on capillary recurved slender pedicels; empty scales acuminate, usually rough or hirsute, the first 1-nerved, the second longer, 3-nerved; flowering scales 4"-6" long, acuminate, 7-nerved, usually rough or hirsute; awn 6"-8" long.
Bromus sterilis L. Sp. PI. 77. 1753.
Culms 1°-2° tall, erect, simple, smooth and glabrous. Sheaths usually shorter than the internodes, smooth or rough, the lower sometimes pubescent; ligule 1" long; blades 3'-9' long, l"-3" wide, usually more or less pubescent; panicle 5'-10' in length, the branches ascending or often widely spreading, not one-sided, stiff; spikelets few, 5-10-flowered, spreading or pendulous; empty scales acuminate, glabrous, the first 1-nerved, the second longer, 3-nerved; flowering scales 6"-8" long, acuminate, 7-nerved, scabrous on the nerves, the awn 7"-12" long.
In waste places and ballast, eastern Massachusetts to District of Columbia, Ohio, Arkansas and Colorado. Also on the Pacific Coast, and in Jamaica. Naturalized or ad-ventive from Europe. Native also of Asia. June-July.
Bromus madritensis L. Amoen. Acad. 4: 265. 1755.
Culms 1°-2° tall, tufted, smooth and glabrous. Sheaths smooth, glabrous, or the lower ones pubescent, usually shorter than the internodes; ligule scarious, lacerated, 1"-2" long; blades 2 1/2'-8' long, 1 1/2"-3" wide, rough above, often pubescent on both surfaces; panicle dense, 3'-6' long, its rough branches erect or ascending, the longer 2'-3' long; spikelets numerous, 1 1/2'-2' long, including the awns, the scales acuminate, scarious on the margins, the first scale 1-nerved, the second 3-nerved; flowering scales, exclusive of the awn, 6"-7" long, sparsely and minutely appressed-pubescent, the apex acumi-nately 2-toothed, 5-nerved, bearing an erect or divergent awn 6"-9" long.
Waste places, Michigan and Virginia; also in California. Locally adventive from Europe. Summer.
Bromus rubens L. and Bromus maximus L., European species, are both reported as sparingly introduced in one or two localities.