506 
30. P.cc” x.nguineum Kth. Culms4to&8 din. high, branching, usually pubescent: 
leaves 1 to 2 dim. long, 1 em, wide or less, rather rigid, tapering toward the involute 
points, often pubescent especially on the sheaths: panicle 5 to 10 cm. long; branches 
spreading, subdivided, and spikelet-bearing to the base: spikelets 2 to 3 mm. long, 
obovate, finely pubescent; first glume acute, one-third as long as the second and 
third; these equal, 9-nerved, barely equaling the smooth floret.— Eastern Texas and 
eastward to Georgia. 
NoTE.—Some narrow-leaved forms of P. scoparium may be looked for here. 
++ ++ Spikelets less than 2 mm. long: leaves usually lanceolate and divaricate. 
31. P. laxiflorum Lam. Culms2 to 5 dm. high, branching below: leaves numerous, 
flat, 1 to 2. dm. long, villous pubescent on the sheaths and sometimes throughout: 
a 
panicle 5to 10cm. long; branches spreading, subdivided to the base, sparingly hairy: 
spikelets nearly 2 mm. long, oval, finely pubescent; first glume deltoid, one-fourth 
as long as the second and third; these obtuse, equal, about equaling the smooth 
floret.—Woods, eastern Texas and eastward. Variable and difficult to distinguish 
from some forms of 2, dichotomum. 
32. P. nitidum Lam. Culms 3 to 6dm. high, simple or with few inconspicuous 
branches: leaves 4 to 8 em. long, rather thick, usually smooth: panicle pyramidal 
or broadly oval, 3 to 6em. long; branches spreading, capillary, subdivided to the 
base, bearing numerous spikelets: spikelets about 1.5 mm. long, oval; first glume a 
minute scale; second and third minutely pubescent, usually purple, equaling but 
often open and disclosing the smooth white floret.—Eastern Texas and eastward to 
the Atlantic. 
33. P. dichotomum L. Culms 2 to & dm. high, at first mostly simple, with flat 
narrowly lanceolate leaves 5 to 10 em. long, smooth or pubescent: panicle broadly 
ovate, spreading, 4 to 8 cin. long; branches capillary, mostly single but diffusely 
subdivided to the base, bearing numerous rather long-pedicelled spikelets: spikelets 
about 1.5 mm. long, oblong or obovate; first glume obtuse, less than one-fourth as 
‘long as the spikelet, often minute; second and third pubescent or nearly smooth, 
about 7-nerved, barely equaling or slightly shorter than the smooth, subacute 
floret. —Common everywhere except in arid regions. Very varible, extending in 
some forms to nearly every other species of this group. Sometimes producing only 
the branching autumnal form, the spikelets of which are often slightly larger than 
those of the exserted panicle, but never 2 mm. long. 
+ + Upper leaves broadly lanccolute with cordate clasping base, somewhat nervose: pani- 
cle often more than 1 dm. long. 
++ Spikelets small, less than 2 mm. long. 
34. P. sphzrocarpon EJ]. Culms 3 to 6dm. high, erect, simple: leaves 5 to 10 
em. long, obscurely nerved, usually ciliate at the cordate base, otherwise smooth, 
or scabrid above: panicle broadly ovate, about 1 dm. long; branches capillary, 
usually single, but diffusely subdivided to the base and appearing fasciculate, bear- 
ing numerous rather long-pedicelled spikelets: spikelets 1.5 mm. long, spherical; 
first glume one-fourth as long as the second and third; these nearly equal, rather 
rough and nervose, usually purple, equaling but at maturity open and disclosing 
the smooth white floret.—Open woods, eastern Texas and eastward to the Atlantic 
States. 
35. P.microcarpon Muhl. Culms 4 to 8dm, high, simple, leafy: leaves divergent, 
1to 2dm. long, prominently nerved, smooth or minutely scabrid above, sometimes 
ciliate at the base: panicle 6 to 12 cm. long, oval or oblong; branches capillary, 
diffusely subdivided to the base, bearing numerous spikelets: spikelets 1.5 mm. long, 
oval; first glume one-fifth as long as the second and third; these minutely pubes- 
cent, equaling the floret.—Low ground, eastern Texas and thoughout the eastern 
United States. 
