MANUAL OF THE GRASSES OF THE UNITED STATES 103 



Blades of the culm and innovations similar. Panicle few-flowered. 



Panicle short, open, the capillary branches bearing 1 or 2 spikelets. 



Culms 10 to 20 cm tall 53. P. vaseyochloa. 



Panicle narrow. 



Lemmas 5 to 6 mm long; panicle usually pale or silvery. 



54. P. PRINGLEI. 



Lemmas less than 4 mm long; panicle usually purple. 



Glumes about as long as the first and second florets; panicle mostly 



not exceeding the short soft blades 55. P. lettermani. 



Glumes shorter than the first floret; panicle usually much longer 



than the usually stiff blades 56. P. leibergii. 



6. Scabrellae 



Sheaths somewhat scabrous 57. P. scabrella. 



Sheaths glabrous. 



Panicle rather open, the lower branches naked at base, ascending or somewhat 



spreading; culms usually decumbent at base 58. P. gracillima. 



Panicle contracted, the branches appressed or at anthesis somewhat divergent. 

 Culms slender, on the average less than 30 cm tall; numerous short innova- 

 tions at base. Blades usually folded 59. P. secunda. 



Culms stouter, on the average more than 50 cm tall; innovations usually 

 not numerous 60. P. canbyi. 



7. Nevadenses 



Sheaths scaberulous. Ligule long, decurrent 61. P. nevadensis. 



Sheaths glabrous. 



Ligule prominent; blades broad and short 62. P. curtifolia. 



Ligule short; blades elongate. 



Blades involute 63. P. juncifolia. 



Blades flat , 64. P. ampla' 



1. Annuae. — Annuals; culms seldom more than 50 cm tall; panicles 

 open (contracted in P. bigelovii). 



1. Poa bolanderi Vasey. (Fig. 160.) Culms erect, 15 to 60 

 cm tall; sheaths glabrous; blades relatively short, 3 to 5 mm wide, 

 abruptly narrowed at tip; panicle about half the length of the entire 

 plant, at first contracted, finally open, the branches few, distant, 

 glabrous, stiffly spreading, naked below; spikelets usually 2- or 3- 

 nowered, the internodes of the rachilla long; glumes broad, 2 and 3 

 mm long; lemma scantily webbed at base, acute, the marginal nerves 

 rather indistinct, the intermediate nerves obsolete. o — Open 

 ground or open woods, 1,500 to 3,000 m, Washington and Idaho to 

 western Nevada and the southern Sierras in California (fig. 161). 



2. Poa howellii Vasey and Scribn. Howell bluegrass. (Fig. 

 162.) Culms 30 to 60 cm tall; sheaths retrorsely scabrous to glabrous; 

 blades narrower than in P. bolanderi, gradually acuminate; panicle 

 one third to half the entire height of the plant, open, the branches in 

 rather distant fascicles, spreading, scabrous, naked below, some short 

 branches intermixed ; spikelets 3 to 5 mm long, usually 3- or 4-nowered ; 

 glumes narrow, acuminate, 1.5 and 2 mm long; lemmas webbed at 

 base, 2 to 3 mm long, ovate-lanceolate, pubescent on the lower part, 

 the nerves all rather distinct. © — Rocky banks and shaded 

 slopes, mostly less than 1,000 m, Vancouver Island to southern Cali- 

 fornia, especially in the Coast Ranges. 



3. Poa bigelovii Vasey and Scribn. Bigelow bluegrass. (Fig. 

 163.) Culms erect, 15 to 35 cm tall; blades 1 to 5 mm wide; panicle 

 narrow, interrupted, 7 to 15 cm long, the branches short, appressed; 

 spikelets about 6 mm long; glumes acuminate, 4 mm long, 3-nerved; 

 lemmas about 3 mm long, sometimes 4 mm, webbed at base, conspicu- 



