94 



POACEAE 



Prolongation of the rachilla 

 with long hairs; 

 flowering scale 

 awned at or below 

 the middle. 



Flowering scale mem- 

 branous; spikelets 8 

 mm. long or less. 



Flowering scale char- 

 taceous; spikelets 10- 

 12 mm. long. 



Tribe VIII. Aveneae 

 Spikelets deciduous; lower flower perfect, upper staminate, 



awned. 

 Spikelets not deciduous; empty scales persistent, flowering 

 ones deciduous. 

 Spikelets of 2 perfect flowers; rachilla not prolonged 



beyond the upper one. 

 Spikelets 2-many-flowered; rachilla prolonged beyond 

 the upper scale. 

 Awn of flowering scale dorsal, inserted below the 

 teeth. 

 Flowers all perfect, or the upper ones stam- 

 inate or wanting. 

 Spikelets less than 12 mm. long; grain 

 free, unfurrowed. 

 Flowering scales convex; awn arising 

 from or below the middle. 

 Awns articulated, the apex club- 

 shaped. 

 Awns not articulated, nor club- 

 shaped. 

 Flowering scales keeled; awn arising 

 from above the middle. 

 Spikelets over 12 mm. long; grain fur- 

 rowed, usually adherent to the scales. 

 Upper flower perfect, lower staminate, its 

 scale strongly awned. 

 Awn from between the lobes or teeth of flowering 

 scale, generally twisted. 



Tribe IX. Chlorideae 



Spikelets deciduous, entire. 



Spikelets not deciduous entire, empty scales persistent; 

 flowering scales deciduous. 

 One perfect flower in each spikelet (rarely 2 in No. 49). 

 No empty scales above the flower. 

 One to several empty scales above the flower. 



Spikelets scattered or remote in long filiform 

 spikes. 



37. Calamagrostis. 



38. Ammophila. 



41. nothoholcus. 



42. Aspris. 



43. Corynephorus. 



44. Deschampsia. 



45. Trisetum. 



46. AVENA. 



47. Arrhenatherum. 



48. Danthonia. 



50. Spartina. 



49. Capriola. 



51. Gymnopogon. 



