52 



4. Glumes three (only one in Coleanthus, or occasionally four in 



some species of Sporobolus and Muhlenbergia) , the first two 

 empty; palea 2-nerved or nerveless, very rarely 1-nerved 

 (Cinna) or wholly wanting (Alopecurus and some species of 

 Agrostis) Tribe VIII. Agrostide^e. (See page 57) 



5. Culms herbaceous, annual; leaf blade continuous with its 



sheath - . 6 



5. Culms woody, perennial; leaf blade articulated with its 



sheath Tribe XIII. B ambuse.e. (See page — ) 



6. Spikelets pedicellate, in panicles, spike-like panicles, or ra- 



cemes, these never unilateral 7 



6. Spikelets sessile, in true spikes, or on very short pedicels in 



unilateral racemes ° 



7. Empty glumes generally longer than the first flowering glume; 



one or more of the flowering glumes awned on the back or 

 from between the teeth of the bifid apex (some cultivated 

 forms excepted); awn twisted, usually geniculate, very 

 rarely straight Tribe IX. Avene2e. (See page 87) 



7. Empty glumes generally shorter than the floral glume; flower- 



ing glume awnless or with from one to many terminal (very 



rarely dorsal) straight or simply divergent awns 



Tribe XL Festuce;e. (See page 112) 



8. Spikelets in unilateral spikes or racemes, these racemed, digitate 



or fasciculate Tribe X. Chlorides. (See page 97) 



8 Spikelets inserted on the alternate teeth or notches of the 

 rachis forming equilateral, flattened, or cylindrical terminal 

 spikes Tribe XII. Hordejs. (See page 157) 



