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..
Panicum capillare L. Sp. PI. 58. 1753.
Culms erect or ascending, 1°-2° tall, simple or sometimes sparingly branched. Sheaths papillose-hispid; blades 6'-1° long, 3"-8" wide, more or less pubescent; terminal panicle generally 8'-14' long, lower branches at first included in the upper sheath, finally exserted and spreading, 6'-10' long; lateral panicles, when present, smaller; spikelets 1"-1 1/4" long, acute; first scale one-fourth to one-half as long as the spikelet; second and third scales nearly equal, exceeding the fourth.
Annual. Culms 8-18' tall, smooth and glabrous; sheaths papillose-hispid with spreading hairs; blades up to 5' long, 2"-5" wide, lanceolate, hirsute; panicle occupying usually more than 1/2 of the plant, much-exserted, broader than long, its branches widely spreading or the lower ones reflexed, the pulvinus in the axils well-developed and strongly hirsute; spikelets 1 1/2"-1 3/4" long, acuminate, glabrous, the scales acuminate, the first 1/2 as long as the second which is longer than the third, the fruiting scale 2/3 as long as the spikelet.
In dry places, Wisconsin to British Columbia, Nebraska, Texas and California. Aug. and Sept.
Panicum capillare var. campestre Gattinger, Tenn. Fl. 94.
1: 123. 1896. Panicum Gattingeri Nash, in Small, Fl. SE. U. S. 92. 1903.
Annual. Culms slender, hispid, finally branched at all of the nodes and the branches again dividing, often prostrate at the base, 1°-2° long, or rarely depauperate and but a few inches high; sheaths papillose-hirsute; blades 6' long or less, 2"-3" wide, pubescent to nearly glabrous, erect; primary panicle 4'-6' long, its branches ascending, the larger ones usually 2'-3' long, the lateral panicles smaller; spikelets about 1" long, elliptic, acute, glabrous.
In poor, often moist soil, Maine to North Carolina, Iowa and Missouri. Aug.-Oct. Illustrated for P. capillare L. in the first edition.
Not P. sylvaticum Lam. 1797. Panicum diffusum Pursh, Fl. Am. Sept. 1: 68. 1814.
Culms erect, or occasionally decumbent, 8'-2° long, slender, often branched at base. Sheaths hirsute; blades 2'-4' long, 1"-3" wide, erect, more or less pubescent; panicle 4'-9' long, its lower branches 3'-4' long, spreading or ascending; spikelets about 3/4" long, elliptic, acute, smooth, borne commonly in pairs at the extremities of the ultimate divergent divisions of the panicle; first scale about one-third as long as the equal acute second and third ones, which barely exceed the fourth.