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..
Agrostis arachnoides Ell. Bot. S. C. & Ga. 1: 134. 1817.
Not Poir. 1810. Agrostis Elliottiana Schultes, Mant. 2: 202. 1824.
Culms 5'-14' tall, erect, slender, simple, smooth and glabrous. Sheaths shorter than the internodes, smooth or slightly scabrous, strongly striate; ligule 1" long; blades rough, 1/2'-2.' long, 1" wide or less; panicle 2'-5' in length, usually narrow, sometimes open, the branches slender, naked below, erect or ascending, the lower l'-l 1/2' long; spikelets 3/4" long; outer scales subequal, scabrous on the keel, acute; third scale about three-quarters as long as the first, erose-truncate, acute or 2-toothed, bearing a very finely filiform flexuous bar-bellate awn, 2-4 times its length, inserted just below the apex; palet short.
In dry soil, South Carolina to Kentucky and Kansas, Florida and Texas. Spider Bent-grass. May-July.
Agrostis rupestris Allioni, Fl. Pedem. 2: 237. 1785-
Culms tufted, 6' or less tall, slender, erect, or decumbent at the base, smooth and glabrous. Sheaths longer than the internodes; ligule about 1/2" long; blades smooth and glabrous, those on the culm 1' or less long, the basal leaves from one-third to one-half as long as the culms; panicle contracted, 1' or less long, its axis and branches smooth, the latter erect or nearly so, spikelet-bearing above the middle; spikelets about 1" long; empty scales about equal, 1-nerved, acute, usually purple, hispidulous on the keel; flowering scale shorter, hyaline, denticulate at the obtuse or truncate apex, bearing about the middle a dorsal scabrous awn a little over 1" long; palet wanting.
Labrador. Also in Europe. Summer.
Agrostis canina L. Sp. PI. 62. 1753.
Culms 1°-2° tall, erect, slender, simple, smooth and glabrous. Sheaths shorter than the internodes; ligule 1/2"-1 1/2" long; blades 1'-3' in length, 1" wide or less, scabrous; panicle 2'-7' in length, contracted in fruit, the branches slender, naked below, ascending or spreading in flower, the lower 1'-2 1/2' long; spikelets 1" long, on appressed pedicels, the outer scales subequal, acute, strongly scabrous on the keel; third scale about two-thirds the length of the first, obtuse, smooth and glabrous, bearing a straight or somewhat bent dorsal awn 1"-2" long, inserted just above the middle; palet minute or none.
In meadows, Newfoundland to Alaska, south to Pennsylvania and Tennessee. Native northward; naturalized from Europe southward. Rhode Island or Dog Bent-grass; Fine-top, Furze-top. Much used for lawns. July-Sept.