152 GRAMINEAE 



Glumes 1 to 2 liues long. 



Panicles open ; glumes 2 lines long 6. P. olneyae. 



Panicles almost spike-like; glumes 1 line long 7. P. atropurpurea. 



Lemmas webbed at base, sometimes sparingly so. 



Culm conspicuously flattened 8, P. cumpressa. 



Culm terete or nearly so. 



Lemmas not pilose on keel or nerves. 



Panicle contracted ; web sparse 9. P. confiiiis. 



Panicle open ; web abundant 10. P. kelloggii. 



Leumias pilose on keel and usually also on marginal nerves. 



Panicle dense and spike-like; plants dioecious 11. P. douglasii. 



Panicle more or less o]>en ; plants not dioecious. 



Lemmas 1 \-2 lines lung 12. P. pratensis. 



Lemmas 2% lines long 13. P. rhizomata. 



Creeping rhizomes absent. 



Lemmas villous on keel and marginal nerNCi; Iilades firm, folded. 



Ligule 21/2 to 3% lines long, acute L-"i. P. longiligula. 



Ligule short, rounded or truncate 14. P. fendleriana. 



Lenmias sometimes pubescent near base but not villous on keel and marginal nerves. 

 Lenunas pubescent on lower part. 

 Blades filiform. 



Panicle spike-like 18. P. nudata. 



Panicle loose and open 19. P. tenerrima. 



Blades narrow but not tiliform. 



Sheaths scabrous; panicle usually narrow 10. P. scabrella. 



Sheaths smooth; panicle usually comparatively short and open. 



Blades scattered along culm ; culms loose and decumbent at base ; spikelets 3 to 4 



lines long 20. P. alcea. 



Blades mostly basal. 



Panicle open; culms decumbent at base 21. P. graciUima. 



Panicle contracted; culms erect 17. P. sandbergii. 



Lemmas smooth or scaberulous. 



Panicle close and spike-like; plants of sea-side cliffs 22. P. unilateralia. 



Panicle more or less open. 



Spikelets 1 or 2-flowered; panicle long, open 23. P. thurberiana. 



Spikelets 3 to several-flowered. 

 Blades filiform. 



Blades smooth 24. P. hanseni. 



Blades scabrous 25. P. idahoensis. 



Blades narrow but not filiform. 



Sheaths scabrous; panicle long, narrow 26. P. nevadenxis. 



Sheaths smooth. 



Panicle narrow, 4 to 8 inches long; culms 1% to 3 feet high 



27. P. brachyglossa. 

 Panicle short, 1 to 2 inches long; culms lower; blades involute, firm. 



Lemmas about 3 lines long 28. P. pringlei. 



Lemmas 11^ to 2 lines long. 



Culms 3 to 8 inches high; blades smooth 29. P. leibergii. 



Cuhns 1 to 2 feet high; blades scabrous 30. P. cottoni. 



1. P. annua L. Annual; enlms flattened, decumbent at base, sometimes 

 rooting at the lower nodes ; sheaths loose ; blades soft and lax ; panicle pyra- 

 midal, open, 1 to 3 inches long; spikelets crowded, 3 to 6-flowered, about 2 

 lines long; lemma not webbed at base, distinctly 5-nerved, the nerves pilose on 

 lower half. 



Open ground, along roadsides and in waste places, throughout the state, 

 except in the deserts ; extends from Alaska to Mexico ; introduced from 

 Europe. 



