202 



POACEAE 



11. Poa nervosa (Hook.) \ asey. 

 Hooker's Bluegrass. Fig. 463. 



Festnca nervosa Hook. Fl. Bor. Am. 2: 251. pi. 232. 1840. 

 Poa nervosa Vasey, U. S. Dept. Agr. Div. Bot. Bull. 13- 



pl. 81. 1893. 

 Poa olneyae Piper, Erythea 7: 101. 1899. 



Perennial, from creeping rhizomes ; culms 30-60 

 cm. tall ; sheaths smooth or the lower scaberulous, 

 rarely retrorsely puberulent ; ligule 1-2 mm. long; 

 blades mostly flat, rather thin, smooth beneath, 

 scaberulous above, as much as 4 mm. wide ; panicle 

 open, the slender branches flower-bearing only at 

 the extremities, lemmas typically strongly nerved, 

 smooth or nearly so, sometimes scaberulous, rarely 

 minutely pubescent. 



Moist rocks and banks, Humid Transition Zone; British 

 Columbia to California. May-Aug. Type locality: Nootka 

 Sound. 



12. Poa kelloggii Vasey. 

 Kellogg's Bluegrass. Fig. 464. 



Poa kelloggii Vasey, U. S. Dept. Agr. Div. Bot. Bull. 13": 

 pi. 79. 1893. 



Perennial, from creeping rhizomes ; culms 30-60 

 cm. tall, smooth ; sheaths smooth, mostly basal ; 

 blades flat or folded, scabrous on upper surface ; 

 panicle pyramidal, open, 7-15 cm. long, the branches 

 mostly in ones or twos, slender, spreading or reflexed, 

 bearing a few spikelets toward the extremities ; 

 spikelets rather loosely flowered, 4-6 mm. long ; 

 glumes 2 and 3 mm. long ; lemmas acute or almost 

 cuspidate, 3-4 mm. long, smooth, rather obscurely 

 nerved, conspicuously webbed at base. 



Coast Ranges in the Transition Zone; Oregon (Corvallis) 

 to Santa Cruz County, California. May-June. Type locality: 

 Mendocino County. 



13. Poa pratensis L. 



Kentucky Bluegrass. Fig. 405. 



Poa pratensis L. Sp. PI. 67. 1753. 



Perennial, from creeping rhizomes ; culms tufted, 

 30-100 cm. tall, terete or slightly flattened; sheaths 

 smooth, compressed ; ligule about 2 mm. long ; blades 

 soft, flat or folded, the basal often elongated; panicle 

 pyramidal, open, the slender branches in remote 

 fascicles of 3-5, ascending or spreading, naked at 

 base, some of them short; spikelets crowded, 3-5- 

 flowered, 4-5 mm. long; lemmas 3 mrn. long, copi- 

 ously webbed at base, silky-pubescent on the keel 

 and marginal nerves, the intermediate nerves promi- 

 nent. 



Open woods, banks, open ground, widely distril)uted ex- 

 cept in the deserts; extending throughout the northern part 

 of North America and Eurasia; escaped from cultivation. 

 May-Aug. Type locality, European. 



