HOW TO KNOW THE GRASSES 



58b. Panicle three or more times longer than wide; leaf blades usually 

 flat. Fig. 243. 



SACATON Sporobolus wrightii Munro 



Perennial; culms in large tufts, stout 

 and tough, 1 — 2.5 m. tall; panicles up to 

 60 cm. long, the branches bearing spike- 

 lets nearly to their bases. The plants 

 furnish good grazing when young, and 

 are sometimes cut for hay. River flats, 

 especially where overflows occur. July 

 — September. 



Figure 243 



TRIBE VI. ZOYSIEAE 



la. Spikelets inclosed in spiny burs, the spines hooked at the tips. 

 Fig. 244. 



COCKLEBUR GRASS Tragus berteTonianus Schult. 



Annual; culms 10 — 40 cm. long, spreading. 

 The burs are borne along a slender raceme, 

 from which they fall readily. Each bur con- 

 sists of a group of 2 — 5 spikelets, but the sec- 

 ond glumes of the two lower spikelets are 

 covered with hooked prickles and conceal the 

 remainder. The plants occur on dry open 

 ground in the Southwest and also at scattered 

 points on the east coast where wool is pro- 

 cessed. The burs are readily transported by 

 the wool of sheep. Probably introduced from 

 the old world; extending through the warmer 

 portions of both hemispheres. August — Oc- 

 tober. 



Figure 244 



lb. Spikelets not inclosed in spiny burs 2 



2a. Spikelets falling in groups of 3, all without stalks 3 



2b. Spikelets falling in pairs, each spikelet on a short stalk 



genus Lycurus. Fig. 191. 



129 



