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..
Alopecurus geniculatus L. Sp. PI. 60. 1753.
Glabrous or very nearly so, culms 6'-18' tall, usually decumbent at the base, simple or sparingly branched, smooth. Sheaths usually shorter than the internodes, loose or somewhat inflated; ligule 1 1/2" - 3" long; blades rarely exceeding 3' long, 1/2"-2" wide, rough, especially above; spikes 1' - 3' in length, 2"-4" thick; outer scales of the spikelet slightly united at the base, 1 1/4"- 1 1/2" long, obtuse or subacute, smooth, glabrous except on the pubescent lateral nerves and strongly ciliate keel; third scale somewhat shorter, obtuse, smooth and glabrous, the awn inserted about i above the base of the scale, and extending for about 1" beyond the spikelet.
A. aristulatus Michx. Fl. Bor. Am. 1: 43. 1803.
A. geniculatus var. aristulatus Torr. Fl. U. S. 1: 97. 1824.
Culms 6'-2o' tall, erect or somewhat decumbent at the base; sheaths shorter than the internodes; blades up to 6' long, 1"-2" wide, rough; spikes 1'-3' long, 2"-3" in diameter; spikelets 1"-1 1/4" long, the outer scales slightly united at the base, pubescent, acutish, the keel ciliate, the flowering scale a little shorter, obtuse, glabrous, the awn inserted at or near the middle of the scale, barely exserted beyond the spikelet.
Wet meadows, Maine to Alaska, Pennsylvania and California. June-Aug.
Alopecurus pralcusis L. Sp. PI. 60. 1753-
Nearly or quite glabrous, slender, culms 1°-2 1/2° tall, erect, simple. Sheaths usually much shorter than the internodes, loose or somewhat inflated; ligule about i" long, erose-truncate; blades 1 1/2'-3 1/2' long, 1"-3" wide, scabrous, at least above; spikes 1 1/2'-2 1/2' in length, 4"-6" thick; outer scales of the spikelet united at the base for about one-quarter their length, 2"-3" long, acute, glabrous except the sparingly pubescent lateral nerves and the strongly ciliate keel; third scale slightly shorter, obtuse, smooth and glabrous, the awn inserted about quarter way up the scale and exceeding it.
In meadows, Newfoundland to southern New York, New Jersey and Ohio. Naturalized from Europe. June-July.
Alopecurus alpinus J. E. Smith, Engl. Bot. pl. 1126. 1803.
Culms glabrous and smooth or nearly so, 5'-2° tall, erect, sometimes decumbent at the base, simple. Sheaths generally shorter than the internodes, loose, often inflated; ligule 1"-2" long, rounded at the apex; blades 1'-7' long, 1"-3" wide, smooth beneath, slightly scabrous above; spike 1 1/2' in length or less, 3"-6" thick; outer scales of the spikelet united only at the base, 2" long, obtuse, villous and ciliate; third scale about equalling the outer ones, obtuse, glabrous except at the villous apex, the awn inserted about one-third the way up, a little exceeding the scale.
Greenland and Labrador to Alaska. Also in arctic and alpine Europe and Asia. Summer.