agrostide.t:. 285 



late above tlie empty glumes, not exteiuling above tbe floret, floral 

 glume witli a minute callus, usually bearded at the base. Empty 

 glumes 2, persistent, membranous or hyaline, often unequal, the 

 lower sometimes minute or obsolete, keeled, acute, mucrouate, or 

 sometimes extending into a short awn, first 1-nervod. set'or.d l-H- 

 nerved: floral glume o-5-nerved. firm or slender, obtuse or acute, 

 '2-tootlied, mucronate or very often exteiuling into a slender awn; 

 palea hyaline, 2-keeled. Stamens usually 3. Styles distinci, stig- 

 nuis plumose. Grain narrow, subterete, enclosed by the floral glume 

 and i)alea, but not adherent. 



Grasses very variable in habit, rarely annual, culms often wiry, 

 leaf-blades often very thin. The genus includes GO or nu)re species, 

 most of which are peculiar to North America. Some are I'uund in 

 South America, a few in Asia. 



Bentham observes: '* They connect in many rcsjjccts. S/ipn with 

 J</ms/KS approaching very nearly to the small-flowered Sfi/xr. though 

 having thinner fruiting glumes, and usually with a luore or less 

 hairy rachilla. From AijroKfis they may be distinguished by their 

 narrow oppressed fruiting glume witb a terminal, never dorsal, awn. 

 A very few unawued species are nearly allied to Epicampoi. The 

 infiorescence is very variable." 



A. First glume 2-nervcd, second l-nerved, floral (jhtme 3- 



nerretl (a) 



a. Ligule a mere ring, empty glumes 2-3 mm. long, floral 



glume 2.5-3 mm. long 1 



a. Ligule 0.5-1.5 mm. long, emi)ty glumes 3-4 mm. long, 

 floral glume 3 mm. long 2 



B. Firsf t/hinie sometimes ,i-)ierveil, second l-nerved, floral 

 glume o-nerrcd (b) 



b. Ligule 2 mm. long, ^nnpty glumes 0.5-L7 mm. long, 

 floral glume 3.5 mm. long 3 



b. Ligule 5-7 mm. long, empty glumes 1.2 mm. long, floral 

 glume -i.4 mm. long 4 



C Second glume usu(dlg J-o'-nerrrd, florrfl glume -f-nerred. . (c) 



c. Ligule 1 mm. long, empty glumes 1.5 mm. long, floral 

 glume 1.5 mm. long 5 



