152 



GRAMINEAE 





Glumes 1 to 2 lines 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. compressa. 



Culm terete or nearly so. 



Lemmas rot pilose on keel or nerves. 



Panicle contracted ; web sparse 9. P. con-finis. 



Panicle open; web abundant 10. P. Icelloggii. 



Lemmas pilose on keel and usually also on marginal nerves. 



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



Panicle more or less open; plants not dioecious. 



Lemmas 1% lines long 12. P. pratensis. 



Lemmas 2y 2 lines' long 13. P. rMzomata. 



Creeping rhizomes absent. 



Lemmas villous on keel and marginal nerves; blades firm, folded. 



Ligule 2y 2 to Sy 2 lines long, acute 15. P. longiligula. 



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



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

 Lemmas pubescent on lower part. 

 Blades filiform. 



Panicle spike-like 18. P. nudata. 



Panicle loose and open 19. P. tenerrima. 



Blades narrow but not filiform. 



Sheaths scabrous; panicle usually narrow 16. 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. gracillima. 



Panicle contracted ; culms erect 17. P. sandbergii. 



Lemmas smooth or scaberulous. 



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



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. 



Blades scabrous ........ . ............................. 25. 



Blades narrow but not filiform. 



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



Sheaths smooth. 



P. hanseni. 

 P. idahoensis. 



P. nevadensis. 



Panicle narrow, 4 to 8 inches long; culms 



to 



P. leibergii 

 P. cottoni 



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. pringle 



Lemmas 1% to 2 lines long. 



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



Culms 1 to 2 feet high; blades scabrous ............. 30. 



1. P. annua L. Annual; culms 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. 



