236 A TEXT-BOOK OF GRASSES 



Key to the Genera of Horde^e 



A. Spikelets more than 1 at each node of the rachis. 



B. Spikelets 3 at each node of the rachis, 1- 



flowered, the lateral pair pedicelled, usually 



reduced Hordeum 



BB. Spikelets 2 at each node of the rachis, 2- to 6- (Par. 268) . 



flowered, all alike, 

 c. Glumes none or reduced to short bristles; 



spikes very loose Hystrix. 



cc. Glumes usually equaling the florets; spikes 

 dense. 

 D. Rachis continuous; glumes broad or 



narrow, entire Elymus 



DD. Rachis disarticulating at maturity, (Par. 269). 



glumes slender, extended into long 

 awns, these and the awns of the 

 lemmas making the spike very bristly.SiTANiON. 

 AA. Spikelets solitary at each node of the rachis. 

 B. Spikelets placed edgewise to the rachis; 

 glume 1 except in the terminal spikelet. 



c. Spikelets several-flowered Lolium 



cc. Spikelets 1-flowered. Introduced on the (Par. 261). 



Pacific coast Monerma. 



BB. Spikelets placed flatwise to the rachis; 

 glumes in pairs, 

 c. Spikelets 1-flowered; spikes slender, terete. 



D. Lemmas awnless Lepturus. 



DD. Lemmas awned. Pacific coast Scribneria. 



cc. Spikelets 2- to several-flowered. 



D. Plants perennial (as to species of the 



United States) Agropyron 



DD. Plants annual. (Par. 262). 



E. Glumes ovate, 3-nerved Triticum 



(Par. 263). 



EE. Glumes subulate, 1-nerved Sec ale 



(Par. 267). 



261. Lolium L. — Rye-grass. A small genus of temper- 

 ate Eurasia. Spikelets several-flowered, somewhat resem- 

 bling those of Festuca, the lemma often awned. The 

 genus can be easily distinguished by the position of the 

 spikelets, edgewise to the rachis. The second glume being 

 next the rachis is usually suppressed but is present and 

 equal to the first in the terminal spikelet. Two closely 

 related species are used for lawns, meadows and pastures. 



