390 Onvin 155.- GRAMINE.E. 



a sheathed axillary one below ; spikelets small, J", in pairs, but seeming 2-rowco, 

 very smooth 1C Dcv or wet, Mass, to 111., and S. Aug. 



2 P. laeve MX. (p) Cu^m erect, H 3f; Ivs. broad-linear, hairy at base or smooth; 



spikes 35 ; spikelets (a, o) single, contiguous, in 2 rows on the narrow straightish 

 rachis, round and smooth, If", if. Grassy banks, Ct. to Ind., and S. Aug. 

 /3. filttxsimnm* Strict, tall ; sheaths flattened close on the spikes. 



3 P. angustifollum Le Cont. Cum. wiry, 2 3f ; Ivs. linear-filiform, comprcsscd- 



carinate ; spikes 2 or 3, 12" ; rachis narrow, flexuous ; spikelets round-oval, brown, 



1", in 2 rows, Whole plant glabrous*. U Wet places. Ga., Fla., La. [and S. 



/3. ttmic. Spikes 4 or 5, very slender, 3-rowed; Ivs. and sheaths ciliate. N. J., 



4 P. praecox Walt. Culm erect, 3 4f; Ivs. long, narrow, smooth; sheaths purple, 



smooth or hairy; spikes 3 6, bearded at base, dense ; rachis straight and flat; spkl. 

 orbicular, in 3 rows, often brown, u Swamps, S. May, June. 



5 P. dasypliyllum Ell. Culm rigid, erect, 2 3f; Ivs. linear.. and with the sheaths 



hairy all over; spikes 2 5, large, 2 4' ; spkl. orbicular-oval, near 2", in 2 or 3 rows 

 under the very flexuous rachis. is. Dry fields, S. July Oct. 

 /3. floridanum, Lvs. long and narrow ; spikelets in 3 rows. Damp, S. 



6 P. virgatum L. Culm H 3f; Ivs. broad-linear, ciliate near the base; spikes 



312, 24' ; rachis broad, but narrower than the 34 rows of small (1") roundish 

 tpikelets; glume 3-veined. (T) Mois-t soils, S. July Oct. 



ft. undul al um. Upper glume (pale) undulate-rugous at edge. 



y. lalifbliutn. Lvs. very broad (6 0") ; spikelets larger (H"). 



7 P. racemulosum N. Culm erect, firm, 2 3f; Ivs. long, linear, soft-hairy; spikes 



34, raceme-like, 26'; spkl. oval, in remote pairs, H", the glume 5-veined, tawny. 

 74 Dry soils, S. (P. interruptum C-B.) Aug., Sept. 



8 P. fluitans K. Culms floating or ascending, 12 20'; Ivs. lance-linear, on open 



sheaths; spikes 20 50, 1 2$-' , rachis 1" wide, flat, pointed, out-running the minute 

 white spikelets beneath them. (T) River swamps, 111. to Va., and S. Oct. 



9 P. Walteriauum Schlt. Culm and Ivs. as in P. fluitans. Spikes 35, 23', 



partly sheathed; rachis not out-running the white (1") spkl. Wet, N. J., and S. J1.4- 



10 P. Dlgitaria Poir. Assurgent, 1 2j-f; Ivs. broad-linear, flat, on long sheaths; 

 spikes slender, 35', a pair at top of the long ped. and some axillary sheathed be- 

 low ; spkl. lanceolate, rachis flattened vertically. ii Woods, Va., and S. Jl. Sept. 



IIP. conjugatum Berg. Erect, 1 2f; Ivs. short (> 4'); spikes a pair at top, 

 (rarely axillary), very slender, 3' ; spikelets minute, white, ovate. (\) N. Orl. 



1 2 P. glabrum (Gaud.) Culms decumbent, spreading, 815' ; Ivs. short ; spikes 

 24. spreading, 1 2', slender; spkl. ovate, purple, f", 2-rowed ; tipper gl. equaling 

 the rt., lower minute. (T) Sandy fields, N. J., and S. (P. ambiguum, DC.) Aug. + 

 3 P. distich um L. Culms assurgent, 12 18'; Ivs. broad-linear; spikes 2 or 3, 

 erert, ne.-ir the top, 1 2^' ; rachis linear, narrower than the 2 or 3 rows of whitish 

 ovate H" ^pikelets', u Wet grounds?, S. States. Plant smoothis?h. July, Aug. 



14 P. tristichum Le C. Culm ascending,! 2f; peduncles from the upper joint, 

 13, filiform, each bearing 3 filiform snberect spikes; spkl. whitish, lance-ovate, mi- 

 nute ; rachis ilexiious. Wet places. 11 Ga., Fla., to La. Aug. 



1 5 P. filifYirmc Swtx. Culm filiform, erect. 1 IJ-f; Ivs. short; spikes 20, filiform, 

 erect ; rachis filiform; spkl. oblong, i", in 3's ; lower glume obsolete, upper as long 

 as tlie flower. Dry soils, (I) Ms. to Ky., and S. 



1G P. serotimim t'krg. Decumbent, rooting, luury-villous ; Ivs. shoit (12)', 

 lance-linear; branches each with 3 5 filiform digitate spikes; rachis gtrs!/.n'.; spkl. 

 lance-ovate, striate, minute, it Sandy fields. S. C. to La. Sept., Oct. 



17 P. sauguiiiale Lam. Crab or Finger G. (</) Erect, 1 2f, Ivs. ntf sheaths 

 oftener hairy ; spikes 59, digitate, spreading, 4 G' ; rachis flexuou? ; t-pkl. (c) 

 oblong-lanceolate, H", upper gl. (c) | as long as the flower, (e) lower one miuato. (J 

 Waste ground.-. Aug. Oct. 



