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. latifolium Walt. Fl. Car. 73. 1788. Not L. 1753.
Panicum Walteri Poir. in Lam. Encycl. Suppl. 4: 282. 1816.
Culms erect, 1°-2 1/2° tall, simple, later somewhat dicho-tomously branched above, the nodes densely barbed. Sheaths glabrous or softly pubescent; blades ovate to broadly lanceolate, 2-5' long, 1/2'-1 1/4 wide, cordate-clasping at base, acute, glabrous or softly pubescent; panicle included or somewhat exserted, 2 1/2'-4' long; branches spreading or ascending, bearing few elliptic short-pedicelled appressed spikelets 2"-2 1/2" long; first scale one-third to one-half as long as the pubescent and equal second and third ones; fourth scale about as long as the third.
Panicum clandestinum L. Sp. PI. 58. 1753. Panicum pedunculatum Torr. Fl. U. S. 141. 1824. Panicum decoloratum Nash, Bull. Torr. Club, 26: 570. 1899.
Culms erect or ascending, 1 1/2°-4° tall, rather stout, simple at first, much branched later in the season. Sheaths longer than the internodes, much crowded on the branches, papillose-hispid, especially the upper ones; blades 2'-%' long, 1/2'-1 1/4' wide, cordate-clasping at base, acuminate, smooth and glabrous, the margins ciliate at base; primary panicle sometimes long-exserted, 3'-5' long, its branches ascending; panicles of the branches included in the sheaths, rarely slightly exserted; spikelets 1"-1 1/4" long, pubescent, elliptic; first scale about one-third as long as the spikelet; second and third oval, acutish, 9-nerved, the fourth oval, obtuse, apiculate, whitish, shining.
In thickets and moist places, Maine to Kansas, south to Florida and Texas. June-July.