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..
Annual or perennial grasses with erect or decumbent culms, usually flat leaf-blades, and spicate inflorescence. Spikelets 1-flowered, flattened; scales 3, the 2 lower empty, acute, sometimes short-awned, more or less united below, compressed-keeled; keel ciliate or somewhat winged; third scale truncate or obtuse, hyaline, 3-nerved, awned on the back, subtending a perfect flower and usually a palet; palet hyaline, acute, sometimes wanting. Stamens 3. Styles distinct or rarely united at the base. Stigmas elongated, hairy. [Greek, signifying Fox-tail Grass, in allusion to the spikes.]
Outer scales of spikelet united for half their length, keel smooth to hispid.
Outer scales of the spikelet united for one-quarter their length or less, long-ciliate on the keel.
Scales i"-i 1/4" in length.
Awn inserted at 1/4 above the base of flowering scale, exserted from the spikelet about 1".
Awn inserted at or about middle of scale, barely exserted from spikelet.
Scales 2"-3" in length.
Spike 1 1/2'-2 1/2' long; outer scales glabrous or sparingly pubescent on the lateral nerves.
Spike 1 1/2' long or less; outer scales villous.
Alopecurus myosuroides Huds. Fl. Angl. 23. 1762. Alopecurus agrestis L. Sp. PI. Ed. 2, 89. 1762.
Smooth or slightly scabrous, culms 1°-2° tall, erect, simple. Sheaths shorter than the internodes; ligule 1" long, truncate; blades 1 1/2'-7' long, 1"-3" wide, scabrous, especially above; spike 1 1/2'-4' long, 2"-4" thick; outer scales of the spikelet united at the base for about half their length, narrowly wing-keeled, 2"-2 1/2" long, the nerves smooth or scabrous, sometimes hispid below, especially on the keel; third scale equalling or slightly exceeding the outer ones, smooth and glabrous, the awn inserted near the base, about twice its length, bent.
In waste places and ballast, southern Massachusetts, New York, New Jersey and Pennsylvania. Adventive from Europe. Native also of Asia. July-Aug. Mousetail; Bennet-weed. Black bent. Black couch-grass. Hunger-grass.