MANUAL OF THE GRASSES OF THE UNITED STATES 



129 



Figure 236.— Distribution of 

 Poa pattersoni. 



regions, Montana, Wyoming, Utah, and Colorado; Oregon (Mount 

 Hood) (fig. 236). 



48. Poa rupicola Nash. Timberline bluegrass. (Fig. 237.) 



Culms densely tufted, erect, rather stiff, often 

 scaberulous below the panicle, 10 to 20 cm tall; 

 blades short, 1 to 1.5 mm wide; panicle narrow, 

 purplish, 2 to 4 cm long, the short branches as- 

 cending or appressed; spikelets usually purple, 

 about 3-flowered; lemmas villous below on keel 

 and marginal nerves 

 and sometimes pubes- 

 cent on the internerves 

 below. Ql — Kocky 

 slopes, British Colum- 

 bia, south in the moun- 

 tains, at high altitudes 

 through Montana to 

 northern New Mexico, 



Arizona, Oregon (Mount Hood and Wallowa 

 Mountains), and California (Mono Pass, Sheep 

 Mountain) (fig. 238). Small specimens of P. 

 interior, which resemble this, differ in having a 

 small web at the base of the lemma. 

 5. Epiles. — Perennials without rhizomes; lem- 

 mas not webbed at base, glabrous or sca- 

 brous (minutely pubescent in P. unilateralis) . 

 49. Poa involuta Hitchc. (Fig. 239.) In 

 dense pale tufts; culms slender, 30 to 40 cm tall; 

 ligule very short; blades involute, slender, 15 to 25 

 cm long, glabrous or slightly scabrous; panicle open, 

 10 to 15 cm long, the branches in pairs, few-flowered 

 near the ends; spikelets mostly 3- or 4-flowered, 5 

 to 6 mm long; lemmas 3 to 4 mm long, scabrous. 

 Qi — Known only from the Chisos Mountains, Tex. 



50. Poa cusickii Vasey. 



CUSICK BLUEGRASS. (Fig. 240.) 



Culms in dense often large 

 tufts, erect, 20 to 60 cm tall; 

 ligule very short; blades fili- 

 form, erect, scabrous, mostly 

 basal; panicle usually pale or 

 tawny, narrow, oblong, con- 

 tracted, or somewhat open at 

 an thesis, 3 to 8 cm long; spikelets 7 to 9 mm long; 

 lemmas 4.5 to 6 mm long, smooth or scabrous. % 

 — Dry or rocky slopes at medium and high alti- 

 tudes, Alberta to British Columbia, south to Col- 

 orado, Nevada, and the central Sierras of California Fl c'o?« E ^r T* n°t? x % 



(fig. 241). floret, X 10. (Swal- 



51. Poa unilateralis Scribn. (Fig. 242.) Culms in 

 dense tufts, 10 to 40 cm tall, sometimes decumbent at base; sheaths 



Figure 235. — Poa pattersoni 

 Plant, X 1; floret, X 10. 

 (Patterson 154, Colo.) 



Figure 238.— Distribution of 

 Poa rupicola. 



