390 ORDER 



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

 very smooth 2; Pry 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. ti) single, contiguous, in 2 rows on the narrow straightisb. 

 rachis, round and smooth, 1p". if. Grassy baivks, Ct. to Ind., and S. Aug. 

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



3 P. ang-ustifolium Le Cont. Cuin. wiry, 2 3f ; Ivs. linear-filiform, compressed- 



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



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



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



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



smooth or hairy ; spikes 36, bearded at base, dense ; rachis straight and flat ; spkl. 

 oibicular, in 3 rows, often brown. 2f 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 

 tinder the very flexuous rachis. it Dry fields, S. July Oct. 

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



6 P. virgatum L. Culm 11 3f: Ivs. broad-linear, ciliate near the base; spikes 



3 12, 2 4' ; rachis broad, but narrower than the 3 4 rows of small (1") roundish 

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



/3. undulhlu.n. Upper glume (pale) undulate-rugous at edge. 



y. lati folium. Lvs. very broad (G 0") ; spikelets larger (1J"). 



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



3 4, raceme-like, 2 (' ; spkl. oval, in remote pairs, li", the glume 5-veined, tawny. 

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



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



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

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



9 P. Walteriaiium 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. Jl.-f- 



10 P. Dlgitarla Poir. Assurgent, 1 2Jf; 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. 11 Woods, Va., and S. Jl. Sept. 



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

 (rarely axillary), very slender, 3' ; spikelets minute, white, ovate. (T) N. Orl. 



12 P. glabrum (Gaud.) Culms decumbent, spreading, 8 15'; Ivs. short; spikes 

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

 the fl., lower minute. Sandy fields, N. J., and S. (P. ambiguum, DC.) Aug. t- 

 3 P. disticli.um L. Cr.lms assurgent, 1218'; Ivs. broad-linear; spikes 2 or 3, 

 erect, near the top, 1$ 2J' ; rachis linear, narrower than the 2 or 3 rows of whitish 

 ovate ]J" spikelets. u Wet grounds, S. States. Plant smoothish. July, Aug. 



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

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

 nute ; rachis flexuous. Wet places. U Ga., Fla., to La. Aug. 



15 P. fillforrtie Swtz. Culm filiform, erect, 1 l}f; Ivs. short; spikes 2 6, filiform, 

 erect; rachis filiform; spkl. oblong, 1", in 3's ; lower glume obsolete, upper as long 

 as the flower. Dry soils, (T) Ms. to Ky., and S. 



16 P. serotinum I'lgg. Decumbent, rooting, hairy- villous ; Ivs. shoit (12)', 

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

 lance-ovate, striate, minute. 7i Sandy fields. S. C. to La. Sept., Oct. 



17 P. sanguinale Lam. Crab or Finger G. (<I) Erect, 1 2f, Ivs. .?<? sheaths 

 oftener hairy; spikes 5 9, digitate, spreading, 46'; rachis flexuout ; tpkl. (c) 

 oblong-lanceolate, If, upper gl. (c) } as long as the flower, (e) lower one tain ato. (J 

 Waste grounds. Aug. Oct. 



