MANUAL OF THE GRASSES OF THE UNITED STATES 



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times pubescent on the internerves 

 below. % — Rocky slopes, British 

 Columbia, south in the mountains, at 

 high altitudes, South Dakota (Black 

 Hills) and Montana to Oregon 

 (Mount Hood and Wallowa Moun- 

 tains); New Mexico, and California 

 (Mono Pass, Sheep Mountain). Small 

 specimens of P. interior, which re- 

 semble this, differ in having a small 

 web at the base of the lemma. 

 6. Epiles. — Perennials without rhi- 

 zomes; lemmas not webbed at 

 base, glabrous or scabrous (mi- 

 nutely pubescent in P. unilat- 

 eralis) . 



52. PoainvolutaHitchc. (Fig. 165.) 

 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 sca- 

 brous; 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, sca- 

 brous. % — Known only from the 

 Chisos Mountains, Tex. 



53. Poa cusickii Vasey. Ctjsick 

 bluegrass. (Fig. 166.) Culms in 



dense often large tufts, erect, 20 to 

 60 cm. tall; ligule very short; blades 

 filiform, erect, scabrous, mostly basal; 

 panicle usually pale, tawny, or pur- 

 ple-tinged, narrow, oblong, contracted 

 or somewhat open at anthesis, 3 to 

 8 cm. long; spikelets 7 to 9 mm. 

 long; lemmas 4.5 to 6 mm. long, 

 smooth or scabrous. QJ. — Dry or 

 rocky slopes at medium and high 

 altitudes, Alberta to British Colum- 

 bia, south to North Dakota, Colorado, 

 and the central Sierras of California. 

 A form with elongate blades and 

 laxer panicle has been differentiated 

 as P. filifolia Vasey; Idaho and 

 Washington. 



Figttke 167. — Poa na- 

 pensis. Floret, X 10. 

 (Duplicate type.) 



Figure 166. — Poa cusickii. Panicle, X 1; floret, X 10. 

 (Howell 183, Oreg.) 



Figure 168. — Poa unila- 

 teralis. Panicle, X 1; 

 floret, X 10. (Chase 

 5653, Calif.) 



54. Poa napensis Beetle. (Fig. 

 167.) Resembling P. cusickii; ligule 

 about 1 mm. long, decurrent in young- 

 leaves; basal blades filiform, the 

 culm blades 1.5 to 2.5 mm. wide; 

 panicle as in P. cusickii, the spikelets 

 slightly smaller; glumes 3 and 3.5 

 mm. long; lemmas about 4 mm. long, 

 slightly to rather strongly scabrous. 

 % — Known only from Myrtledale 

 Hot Springs, Napa County, Calif. 



55. Poa uniiateralis Scribn. (Fig. 

 168.) Culms in dense tufts, 10 to 40 

 cm. tall, sometimes decumbent at 

 base; sheaths tawny, papery; blades 



