507 
++ ++ Spikelets larger, more than 2 mim, long. 
36. P. commutatum Schultes. Culms 5 to 10 dm. high, erect or somewhat genic- 
ulate, sometimes branching below: leaves 5 to 10 cm. long, divergent, smooth: pan- 
icle 6 to 12 em. iong, broadly ovate or oblong, loose; branches spreading, capillary, 
diffusely subdivided to the base: spikelets slightly more than 2 mm. long, oblong, 
early deciduous; first glume deltoid, one-third as long as the second and third; 
these finely pubescent, subacute, equaling or barely exceeding the smooth floret.— 
Open woods, eastern Texas and eastward. 
37. P. scoparium Lam. Culms 8 to 6 din. high, ereet or decumbent, rather 
weak, rough, often pubescent: leaves 5 to 10 cm. long, ciliate on the margins, often 
pubescent throughout; sheaths papillose pubescent: panicle oblong, open, 4 to 8 
em. long; branches ascending, hispid or pubescent, with few subdivisions: spikelets 
about 3mm. long, pubescent or nearly smooth; first glume about one-fourth as long 
as the second and third; these 7 to 9-nerved, equaling the floret.—Thickets and 
moist land. 
38. P. latifolium L. Culms 3 to 6 dm. high, leafy, mostly simple, often pubes- 
cent or barbulate at the nodes: leaves about 1 dm. long, 2 to 3em. broad, smooth 
or thinly pubescent, woolly at the throat: panicle5 to 10 em, long, broad and open; 
branches mostly single with few subdivisions: spikelets mostly short-pedicelled, 3 
to 4 mm. long, obovate; first glume acute, one-third as long as the second and third; 
these pubescent, 1l-nerved, equaling the smooth subacute floret.—Moist thickets, 
eastern Texas and eastward. 
39. P. clandestinum L. Culms 6 to 12 dm. high, rather robust, leafy to the top: 
leaves 1 to 2 dm. long, smooth except the hispid margins; lower sheaths papillose 
pubescent: panicle usually included in the upper sheath until after flowering, 
exserted at maturity, 1 to 1.5 dm. long; branches subverticillate, ascending: spike- 
lets 3mm, long; first glume ovate, about one-half as long as the second and third; 
these 9-nerved, slightly pubescent.—Oen woods, eastern Texas and northeastward. 
+ + Leaves lanceolate, very slightly or not at all cordate-clasping: panicle 7 to 2 dm, long. 
40. P. viscidum Ell. Culins 5 to 10 dm. high, rather stout, leafy to the top, vel- 
vety pubescent throughout, except a narrow ring below each node: leaves | to 3 dm. 
long; sheaths and usually the biades velvety: panicle 1 to 2 dm. long; branches 
ascending or spreading, diffusely subdivided to the base: spikelets 2mm, long; first 
glume one-fourth as long as the second and third; these pubescent, 7 to 9-nerved, 
barely equaling the smooth obtuse tloret.—Moist land, eastern Texas and eastward. 
41. P. scabriusculum Chapm. Culms 8 to 12 dm. high, smooth, usually with 
short branches at the middle nodes, rigid, leafy: leaves rather thick and firm, smooth, 
1.5 to 3 dm. long, slender pointed: panicle broadly oval, 1 to 2 dm. long; branches 
ascending, diffusely subdivided, bearing numerous spikelets: spikelets 2 mm. long, 
subacute; first glume less than one-fourth as long as the second and third; these 
9-nerved, nearly smooth.—Low land, southern and eastern Texas and eastward to 
Florida. 
* * Spikelets acute or acuminate. 
+ Culms low, less than 1m. high, except in some forms of No. 46: panicle diffuse. 
++ Spikelets long (6 mm, long). 
42. P. capillarioides Vasey. Perennial: culms 3 to 5 mm. high, tufted, branch- 
ing below: leaves narrowly lanceolate, 1 to 3 dm. long, pubescent on the sheaths 
and often on the blades: panicle 1 to 2 dm. long, loose; branches capillary, spread- 
ing, 1 dm. long or less, bearing rather short-pedicelled spikelets, clustered at the 
ends of the branches and divergent subdivisions: spikelets narrowly conical, 4 to 5 
min. long; first glume 5-nerved, equaling the floret and one-third as long as the 
many-nerved second and third.—Duval County, southern Texas. 
