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..
P. pauciftorum Ell. Bot. S. C. & Ga. 1: 120. 1817.
Not R. Br. 1810. P. oligosanthes Schult. Mant. 2: 256. 1824.
Culms tufted, erect, 1°-2 1/2° tall, villous, finally branched; sheaths, especially those on the branches, papillose-hispid, ciliate on the margin; blades erect or ascending, 2'-4' long, 2 1/2"-5" wide, lanceolate to linear, softly and densely pubescent on the lower surface, the upper surface glabrous or with a few long hairs near the base; primary panicle 2'-4' long, its branches ascending; spike-lets 1 3/4"-2" long and about i as wide, oval, pubescent.
In dry soil, New Jersey to Florida, Illinois and Texas. June-Sept.
Plant light green, becoming yellowish in drying. Culms erect, 1°-2° tall, simple. Sheaths sparingly papillose-pubescent; ligule very short; blades 3'-6' long, 1/3'-3/4' wide, rounded at base, long-acuminate, erect, smooth and glabrous; panicle long-exserted, linear, 1 1/2'-4' long, its branches appressed, rarely somewhat ascending; spikelets few, 1 1/2"-2" long, obovoid, pubescent or rarely glabrous, first scale about one-half as long as the nearly equal obtuse second and third; fourth scale indurated and shining, elliptic or oval.
Dry soil, Quebec to Manitoba and Pennsylvania. June-Aug.
Panicum Wilcoxianum Vasey, Bull. U. S. Dept. Agric. Bot. Div. 8: 32. 1889.
Culms erect, 6'-10' tall, sparingly pubescent. Sheaths papillose-hispid; ligule a ring of hairs; blades 1 1/2'-3' long, less than 2" wide, long-acuminate, strongly pubescent with long hairs; panicle about 1 1/2' long, about one-half as wide, oblong to ovoid, compact; branches less than 1' long, ascending, flexuous; spikelets 1 1/4"-1 1/2" long, ellipsoid; first scale about one-quarter as long as the spikelet; second and third scales about equal, pubescent; fourth scale about as long as the third, obtuse.
In dry soil, North Dakota to Manitoba, Iowa and Kansas. July-Aug.
P. scoparium Chapm. Fl. S. St. 575. 1860. Not Lam.
Culms tufted, erect, 16'-2° tall, finally branched, papillose-hispid below with spreading or ascending hairs, the pubescence above softer; sheaths densely papillose-hirsute with ascending hairs; blades 3'-$' long, 5"-10" wide, cordate at the clasping base, broadly lanceolate, erect or ascending, glabrous on the upper surface, densely and softly pubescent on the lower surface; panicle 3'-5' long, its branches ascending; spikelets about 2" long and nearly 1/2 as wide, obovoid, pubescent with rather weak hairs.