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..
Sporobolus canovirens Nash, in Britt. Man. 1042. 1901.
Culms 1°-3° tall, erect; leaf-blades 10' long or less, 1/2"-1 1/2" wide, attenuate and filiform above; panicle 2'-5' long; spikelets 2 1/2"-3" long, the scales acuminate, the empty ones unequal, the flowering scale appressed-pubescent below with long hairs, about equalling or a little exceeded by the acute palet.
S. Drummondii Vasey, Cat. Grasses U. S. 44. 1885.
Culms 1 1/2°-3° tall, erect, slender; leaf-blades 1° long or less, 1/2"-1 1/2" wide, attenuate and- filiform at the apex; panicle 4'-6' long, slender; spikelets about 2" long, the empty scales acute, the first shorter than the second, the flowering scale glabrous, acute or obtusish, longer than the second one and about equalling the acutish palet.
In dry soil, Missouri to Louisiana and Texas. Sept.-Oct.
Sporobolus attenuates Nash has been reported as introduced along railroads in Jackson Co., Mo. It is related to the above and may be distinguished by its smaller spikelets about 1 1/2" long.
Culms 1 1/2°-3 1/2° tall, erect, simple or occasionally branched, smooth and glabrous. Sheaths shorter than the internodes; ligule very short, minutely ciliate; leaves 4'-18' long, 1"-2" wide at the base, attenuate into a long slender involute tip, smooth and glabrous beneath, scabrous and hairy at the base above; panicle more or less included in the upper sheath, 3'-10' in length, linear, strict, the branches 1'-2' long, erect; spikelets 2 1/2"s" long; outer scales unequal, acutish, glabrous, the lower shorter; third scale glabrous, acutish or obtuse, exceeding the second and equalling or a little shorter than the obtuse palet.
In dry soil, Maine to South Dakota and Texas. Prairie-grass. Aug.-Sept.
Sporobolus pilosus Vasey, Coult. Bot. Gaz. 16: 26. 1891,
Culms 1°-1 1/2° tall, erect, rigid, stout, smooth and glabrous. Sheaths shorter than the internodes, crowded and overlapping at the base of the culm; ligule very short, minutely ciliate; blades 3'-6' long, 1"-2" wide at base, erect, rigid, attenuate into a slender involute tip, the lower papillose-hirsute on both sides, the upper usually glabrous beneath, scabrous above and somewhat hairy near the base; panicle 2'-3' in length, included at the base, erect, strict, its branches 1/2'-1' long, erect; spikelets 21/2"" long, the outer scales unequal, glabrous, obtuse, the lower shorter; third scale obtuse, glabrous, somewhat exceeding the second and equalling or a little longer than the obtuse palet.
In dry soil, Kansas and Missouri. Aug.-Sept.