HOW TO KNOW THE GRASSES 



22a. Edges of lemma overlapping and hiding the palea; panicle elon- 

 gated, spikelike, with many spikelets. Fig. 207. 



Stipa viridula Trin. 



Perennial; culms 60 — 100 cm. tall, in 

 dense clumps; panicles slender, dense, 

 elongated, 10^ — 20 cm. long. The glumes 

 are glossy and rather translucent. Awn 

 2 — 3 cm. long, with two bends. Dry 

 plains. This species yields good forage, 

 June — August. 



Stipa robusta Scribn. (SLEEPY GRASS) 

 is very similar, but taller (100 — 150 cm). 

 It has a narcotic effect on horses who 

 graze it. Dry plains, Colorado to Texas 

 and Arizona. 



Figure 207 



22b. Edges ol lemma not meeting, turned inward, with a deep groove 

 between the edges; panicle with spreading branches/ bearing a 

 few spikelets near their tips. Fig. 208. 



PINYON RICEGRASS Piptocbaetium iimbriatum (H. B. K.) Hitch. 



Perennial; culms in dense tufts, 40 — 80 cm. 

 tall; leaf blades one-third to one-half as long 

 as the culms, mostly at the base of the plant, 

 thread-Hke and curved downward; panicles 

 5 — 15 cm. long; glumes about 5 mm. long, 

 thin; floret dark-colored, glabrous or hairy; 

 awns readily detachable, twice bent, 1 — 2 

 cm. long. Piiion ricegrass is said to be a 

 valuable forage species. Open, rocky woods. 



The genus Piptochaetium is one of the old- 

 est known grass genera. Fossils of the florets 

 have been collected from Miocene rock for- 

 mations in the western states. 



Figure 208 



111 



