664 POACK.K. 



Thcro arc alwiit 30 rt|KM'iefl, widely diHtributcU over tlio tern- 

 pcriite and somi; of the warmer n'gioiirf of tlio ^'lul>e. It difTfr.s 

 from /W ill liuviii^ tin; llonil ^'liimu round on tlu> hack and not 

 kci'Icd, from Fvsiiini in liavin;.' broador and moro obtuse floral 

 ^dumcs, and tin- ;(rain usually free from the ])alei, and from both 

 in the shortness of the nerves of the jrlnmes. Henthum was some- 

 what in doubt as to whether to inelude Jfropis Hupt. in this <,'enus 

 or not, but linally concluded to do so. The characters given for 

 tlic sections are not constant. 



A. Spikelets ovate, oblong or linear-oblong, 3-8 nun. long, (b) 

 b. Spikelets turgitl, llattened laterally, panicle nodding. 1 

 b. Sjtikclets somewhat turgid and ihittened, panicle 



narrow (c) 



c. Panicle oblong, dense, erect, S-l*> cm. long. . . '2 



c. I'anicle slender, nodding, !i()-:50 cm. long. ... 3 

 b. Floral glume truiu-ate, obtuse, ])aniele ditfuse . . . (d) 



d. Floral glume contracted near the apex, T-nervcd, 

 2.5-3 mm. long i 



d. Floral glume n(»t contracted near the apex . . . (c) 



e. Floral glume obtuse, 7-nerved. l.t-'^' mm. long. ."> 



c. Floral glume obtuse, i- nerved. *i-".'.3 jum. long. <> 

 e. Floi'al glume obtuse, often denticulate. 7- 



nerved, 2.5 mm. long 7 



c. Floral glume obtuse, irregularly toothed. 5-T- 



nervcd, 2.2-3 nun. long S 



B. Spikelets linear. ai)})r<'ssed, terete when not in tlowcr, 



20-;5«) mm. long (I') 



f. Floral glume 3-5 mm. long it 



f. Floral glume 7-8 mm. long 10 



1. P. Canadensis (Miehx.) Kuntze, 1{(V. den. I'!. 7s;j (1S!»1). 

 Bn'zH i'iDHuhnsis Michx. Fl. lior. Am. 1 : 71 (1803). O'li/reriu 

 Canaiknsis Trin. Mem. Acad. St. Petersb. (VI.) 1:300(1831). 



A stout perennial, G0-!>0 cm. high. Sheaths rough, slightly 

 compressed, about the length of the internodes; ligule 2 mm. long; 

 blades G, scabrous, flat, erect, 20-30 cm. long, 4-7 mm. wide. 

 Panicle exserted, oblong-pyramidal, soon drooping, lS-2.5 cm. 



