11 



Stamens three, rarely two ; two persistent glumes 

 below the articulation, two inner ones enclos- 

 ing the grain, two intermediate ones small 

 or enclosing male flowers. 

 Panicle loose. Intermediate glumes enclosing 



male flowers with two-nerved palese ... 47. Hierochloe. 



Tribe V. — SxEEPTATHEBiE. — Spikelets with one, two, or rarely several 

 bisexual flowers, and rarely a male flower above or below. Flowering glume 

 usually bearing an awn twisted in the lower part, bent or divided about the 

 middle. Palea two-nerved, usually thin or small, in a few Avenaceae as large 

 as in Festucaceae. 



(The awn is very small and straight or deficient in a few species of Agrostis 

 and Deyeuxia, the twisted portion below the branches very short or obsolete 

 in one section of Aristida.) 



Subtribe I. — Stipaceae. — Spikelets one-flowered. Awn terminal, simple or 

 three-branched. Lodicules three. Fruiting glume usually narrow, hardened, 

 enclosing the grain. 



Awn three-branched ... ... ... ... ... 48. Aristida. 



Awn simple, at length articulate on the glume ... 49. Stipa. 



Subtribe II. — Agrostidege. — Spikelets one-flowered. Awn either terminal 

 between the lobes of the glume or dorsal, in a few species very small or 

 deficient. Lodicules two. Fruiting glume enclosing the grain, usually thin. 



Awn terminal between the lobes of the glume (two 

 on each side), rhachis of the spikelet not 

 continued beyond the flower ... ... 51. Pentapogon. 



Awn more or less dorsal, sometimes minute or deficient. 

 No bristle continuing the rhachis beyond the 

 flowering glume. 

 Awn fine and near the tip of the glume. 



Palea more than half as long as the glume. 53. Dichelachne. 

 Awn dorsal or none. Palea not more than 

 half the length of the glume or minute 

 or none ... ... ... ... ... 54. Agrostis. 



Ehachis of the spikelet usually produced into a 

 point or bristle beyond the flower or 

 bearing an empty glume. Awn various. 

 Palea more than half as long as the 

 glume ... ... ... ... ... 55. Deyeuxia. 



Subtribe III. — Avenacese. — Spikelets with two or in a few genera more 

 than two perfect flowers (only one in Anisopogon), the rhachis produced 

 above them (except in Aira) . Awn either dorsal or terminal between the 

 lobes of the glume. Grain enclosed in the glume and palea, and sometimes 

 adnate. 



Awn dorsal. 



Flowers both bisexual, the rhachis not at all or 



scarcely produced. Grain adnate ... 5G. Aira. 

 Flowering glumes keeled. Two or three perfect 

 flowers. 

 Awns attached below the middle. Grain free 59. Deschampsia. 

 Awns attached above the middle, grain free, 



glabrous... ... ... ... ... 60. Trisetum. 



