564 POACE^. 



There are about 30 species, widely distributed over the tem- 

 perate and some of the warmer regions of tlie globe. It differs 

 from Poa in liaving the floral glume round on the back and not 

 keeled, from Festuca in having broader and more obtuse floral 

 glumes, and the grain usually free from the palea, and from both 

 in the shortness of the nerves of the glumes. Bentham was some- 

 what in doubt as to whether to include Atrojns Eupt. in this genus 

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

 the sections are not constant. 



A. Spikelets ovate, oblong or linear-oblong, 2-8 mm. long, (b) 

 b. Spikelets turgid, flattened laterally, panicle nodding . 1 

 b. Spikelets somewhat turgid and flattened, panicle 



narrow (c) 



c. Panicle oblong, dense, erect, 8-12 cm. long. . . 2 



c. Panicle slender, nodding, 20-30 cm. long. ... 3 

 b. Floral glume truncate, obtuse, panicle diffuse . . . (d) 



d. Floral glume contracted near the apex, 7-nerved, 

 2.5-3 mm. long 4 



d. Floral glume not contracted near tlic apex . . . (c) 

 e. Floral glume obtuse, 7-nerved, 1.7-2 mm. long. 5 

 e. Floral glume obtuse, 7-nerved, 2-2.3 mm. long. 6 

 e. Floral glume obtuse, often denticulate, 7- 



nerved, 2.5 mm. long 7 



e. Floral glume obtuse, irregularh^ toothed, 5-7- 



nerved, 2.2-3 mm. long 8 



B. Spikelets linear, appressed, terete when not in flower, 



20-30 mm. long (f) 



f. Floral glume 3-5 mm. long 9 



f. Floral glume 7-8 mm. long 10 



1. P. Canadensis (Michx.) Kuntze, Rev. Gen. Pi. 783 (1891). 

 Briza Canadensis Michx. Fl. Bor. Am. 1: 71 (1803). Ghjceria 

 Canadensis Trin. Mem. Acad. St. Petersb. (VI.) 1: 366 (1831). 



A stout perennial, 60-90 cm. high. Sheaths rough, slightly 

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

 blades 6, scabrous, flat, erect, 20-30 cm. long, 4-7 mm. wide. 

 Panicle exserted, oblong-pyramidal, soon drooping, 18-25 cm. 



