33 



smootbisb, lower glume one-third as long as the spikelet. Differs from 

 P. diehotomum in its more rigid, smooth, pale leaves, with cordate 

 base. 



Dry or moist ground, of same range as the next species. 



Var. Floridanum. — Culms 1A to 2J feet bigh, rigidly erect, leaves 

 rigid, erect, six to seven on the culm, lanceolate, smooth, about 3 inches 

 long, 5 to 6 lines wide, the margins near the base, and sheaths ciliate ; 

 panicle oval to oblong, 3 to 5 inches long, and spikelets one-half line 

 long, pubescent, the lower glume one-fourth or one fifth as long as the 

 spikelet. 



Florida. 



Described by Dr. Chapman as P. sphaerocarpou Ell, but it hardly 

 agrees with Elliott's description. It is intermediate between P. micro- 

 car pon and P. spba3rocarpon. 



43. P. microcarpon, Mulil, (P. multiflorum, Ell.). — Culms 2 to 3 feet 

 high, stout, erect, smooth ; leaves 4 to 7 inches long, 9 to 12 lines wide, 

 lanceolate, gradually tapering to a slender point, with nine to eleven 

 nerves, roughish above and on the margin, sometimes bristly-ciliate at 

 the rounded, clasping base, smooth on the under side, sheaths mostly 

 longer than the internodes, smooth except on the margins; ligule 

 nearly obsolete, panicle becoming long-peduncled, 3 to 7 inches long, 

 1 to 2 inches broad, spreading, multiflorous, branches mostly verticil- 

 late, very numerous, flowering to the base, spikelets mostly long-pedi- 

 celed, oval, five-eighths of a line long, nearly smooth, lower glume one- 

 fourth as long as spikelet, second glume 7-nerved. 



Low ground, Massachusetts to Texas. 



44. P. viscidum, Ell.~-Ci\\ms 2 to 4 feet high, stout, becoming much, 

 branched, leafy, velvety-downy all over, except a narrow ring below 

 each node; sheaths soft-downy, the hairs spreading or reflexed and 

 often viscid, leaves down}' or smoothish, lanceolate, 4 to 8 inches 

 long, diffuse, the branches numerous and much subdivided, spikelets 

 fully 1 line long, oblong-obrvate, pubescent, lower glume one-fourth 

 to one fifth as long as the 7 to 9 nerved upper one. 



Common. 



45. P. commutatum, Schultz (P. nervosum, Muhl.). — Culms 2 to 2J 

 feet long, erect, unbranched, rather slender, smooth ; leaves at the base 

 rigid, ovate lanceolate, the three or four culm leaves firm but not rigid, 

 mostly 3 to 4 inches long, 8 to 12 lines wide, acuminate, cordate at 

 base, smooth except on the margins, sheaths smooth or somewhat 

 pubescent, much shorter than the nodes; panicle peduncled, 3 to 5 

 inches long, 2 to 3 inches wide, open, rather thin, branches smooth, 

 single or subverticillate; spikelets rather long-pedicelled, oblong, 

 sparsely hairy, 1 to 1^ lines long, lower glumes one-third as long as the 

 spikelet, second about five, and third seven nerved. A fine species, in 



11244—^0. 8- — 3 



