132 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



01 Rocky alpine summits, Montana to Washington, south to 

 Nevada (Mount Rose) and California (fig. 247). 



55. Poa lettermani Vasey. (Fig. 248.) In low lax tufts; culms 

 mostly less than 10 cm tall, usually scarcely exceeding the blades; 

 ligule 1 to 2 mm long; blades 

 lax, usually not more than 1 

 mm wide; panicle narrow, con- 

 tracted, 1 to 3 cm long; spikelets 

 3- or 4-flowered, 4 to 5 mm long; 

 glumes equal, somewhat acumi- 

 nate, about as long as the first 

 and second florets ; lemmas erose 

 at summit, 2.5 to 3 mm long. 

 <4 Rocky alpine summits, 

 British Columbia, Washington, 

 Colorado (fig. 249). 



56. Poa leibergii Scribn. 

 LEIBERG BLUEGRASS. (Fig.250) 

 Usually densely tufted; culms 

 10 to 30 cm tall, erect; ligule 1 

 to 2 mm long; blades mostly 

 basal, firm, involute, usually 

 FIGURE 246. Poa pringiei. less than 10 cm long; panicle 

 CEta^'wft^ narrow, 2 to 5 cm long, often 

 purple, the branches short, ap- 

 pressed or ascending; spikelets 2- to 4-flowered, 4 to 

 6 mm long; lemmas 3 to 4 mm long, smooth or 

 scaberulous. 21 Alpine meadows and sterile 

 gravelly alpine flats, eastern Oregon and the Sierras 

 of California. 



6. Scabrellae. Perennials, without rhizomes, tufted, with numerous 

 basal leaves; spikelets little compressed, narrow, much longer 

 than wide; lemmas convex, crisp-puberulent 

 on the back towards the base, the keels ob- 

 scure, the marginal and intermediate nerves 

 usually famt. The whole group of Scabrellae 

 is made up of closely related species which 

 appear to intergrade. 



57. Poa scabrella (Thurb.) Benth. PINE BLUE- 

 GRASS. (Fig. 251.) Culms erect, 50 to 100 cm 

 tall, usually scabrous at least below the panicle; 



FIGURE 248 Poa letter- 

 mani. Plant, X 1; floret, 

 X10. (Letterman, Colo.) 



FIGURE 247. Distribution 

 of Poa pringiei. 



FIGURE 249 Distribution 

 of Poa lettermani. 



FIGURE 250. Poa leibergii. 

 Plant, X 1; floret, X 10. 

 (Type.) 



sheaths scaberulous; ligule 3 to 5 mm long; blades mostly 

 basal, 1 to 2 mm wide, lax, more or less scabrous; panicle narrow, 

 usually contracted, sometimes rather open at base, 5 to 12 cm long; 



