158 



.■57. GRAMINE.E. 



A. Spikelets with 2 or more fertile flowers. 

 I. Spikelets sessile in a simple spike. 

 Spikes compressed, 2-raiiked. 

 Spikelets appressed to the axis by 

 one of their sides or edges ; outer 



glume 1 



Spikelets appressed to the axis by 

 one of their flattened faces; outer 



glumes 2 



Spikes cylindrical ; spikelets appressed 

 to the axis by one of their faces 

 (sides of the glumes). 

 Spikelets 3-5-flowered ; outer glumes 



broad, blunt 



Spikelets 2-flowered ; outer glumes 



narrow, pointed 



I. Spikelets subsessile in a contracted 

 spikelike panicle. 



Hairy grass; all spikelets fertile 



Glabrous grass; spikelets fertile and 



sterile 



I. Spikelets in a loose panicle. 



J. Flowers surrounded by long, silky 

 hairs: tall grasses with straight, 



hollow stems 



.J. Flowers without long hairs at the base. 



K. Outer glumes large, membranous, 



enclosing the flowers; flowering 



glume rounded on back. 



Spikelets large ; outer glumes 



many-nei-ved ; flowering glume 



awned 



Spikelets small ; outer glumes 1- 

 nerA'ed ; flowering glume awned 



or not 



K. Outer glumes shorter than the flowers. 



L. Flowering glume bifid, witli awn 



inserted below the summit ; 



ovary hairy; grain adhering to 



palea 



L. Flowering gium(^ entire, awnless 

 or with a terminal awn. 

 Flowering glume rounded on the 

 back, not keeled; grain more 

 or less adhering to the palea. 

 Spikelets drooping and quiver- 

 ing; glumes all boatshaped, 



awnless 



Spikelets erect ; flowering glume 



awned or mucronate 



Flowering glume keeled on the 

 back ; grain free. 

 Spikelets in compact clusters ; 

 flowering glume shortly awned 

 Spikelets not clustered ; flower- 

 ing glume awnless 



Loi.irM 20 



AoROPYRrM 



TRiTicrM 21 

 Sec.\le 22 



KiKLEFlA 23 

 CYNOSrRUS 



Artndo 24 



AVENA 25 /1^ 



AiRA 26 



Bromus 27 'l^ 



Briza 23 /So 

 Festuca 29 



Daitvi.is 30 

 POA 31 



