SPERMATOPHYTA—GRAMINEAE— GRASSES 339 



Fig. 137d. 

 grostis major) . 



Scent glands of stink grass (£r(>> 



Fig. 137c. Spikelets of various grasses. 1. 

 Common blue grass {Poa pratensis). 2. Setaria 

 glaiica. 3. Spikelet of blue-stem grass. 4. Bristly 

 fox-tail (Setaria verticillata). 





A great many grasses, because of their sharp edges on the leaf, inflict 

 injuries by cutting the flesh. Of these we may mention the rice-cut-grass, 

 (Leersia), and porcupine grass, (Spartina cynosuroides). 



Holy grass (Hierochloe odorata) is sweet scented and contains coumarin. 

 Indians use it to weave in baskets, mats, etc. Job's Tears, Coix lachrynia, is 

 used for rosaries. 



KEY FOR GENERA OF GRAMINEAE 



Spikelets jointed upon the rachilla below the glumes, 1-2 flowered. 



Rachis bearded, spikelets spicate in pairs 2. Andropogon 



Rachis not bearded. 



Pedicels bristle bearing 4. Setaria 



Pedicels not bristle bearing. 



Spikelets enclosed by a bur 5. Cenchrus 



Spikelets plano-convex, not enclosed by a bur 3. Paspalum 



Spikelets in pistillate flowers, borne on a cob 1. Zea 



Spikelets not usually jointed above the persistent lower glumes. 

 Spikelets 1-flowered. 



Awn simple twisted 7. Stipa 



Awn 3-pointed 6. Aristida 



Spikelets more than 1-flowered. 



Spikelets 2-several flowered, rachis often bearded, flowering glume 



with a twisted awn 8. Avena 



Spikelets 1 or more-flowered with a zigzag jointed rachis, channeled. 

 Spikelets solitary at the notches. 



