41 



17. Axis very slender. Spikelets strongly curved , 



P. curvatura. 

 Axis stout. Panicle always cylindrical 18 



18. Spikelets olive green, with dark tips. Blades flaccid. 



P. interruptum. 

 Spikelets purplish, slightly curved. Blades rigid .., 



P. typhurum. 



19. Culms either (1) slender to very slender, ascending; or 



(2) compactly caespitose. 20 



Culms robust often very tall. Blades 1-2- ft. by 2-8 lin. 32 



20. Culms very slender ascending from a trailing or rambling 



base many noded, often branched. Leaves ^-3 



inches 21 



Culms slender, compactly caespitose, or if decumbent at 



the base then rather stout. Leaves usually 3-5 



inches 27 



21. Lower valve 7-9 nerved 22 



Lower valve 5 nerved 25 



22. Lower branches of panicle 3-6 in. long. Pedicels |-1J 



ins. long P. perlaxum. 



Lower branches of panicle J-2| ins. long. Pedicels J-l 

 lin. long 23 



23. Spikelets acute to acuminate, often pubescent ... 



P. aequinerve. 

 Spikelets obtuse, glabrous 24. 



24. Leaves glabrous. Jjower glume not more than i length 



of spikelet P. flliculme. 



Leaves finely hairy. Lower glume i length of spikelet. 



P. hymeniochilum. 



25. Panicle large effuse. Spikelets 1 lin. long. P. laticomum. 

 Panicle scanty. Spikelets 1^-2 lin. long 26 



26. Blades shortly petioled. Longer pedicels up to 1^ lin. 



long P- chusqueoides. 



Blades not petioled. Longer pedicels up to 4 lin. long. 



P. obumbralum. 



27. Glumes and lower valve 3-5 toothed P. ecklonii. 



Glumes and lower valve entire 28 



28. Culms 4-many noded, from a creeping rhizome or 



decumbent, branched base 29 



Culms 1-3 (rarely 4) noded, simple; densely caespitose 30 



29. Stoloniferous. Lower leaves distichously imbricate, 14-3 



lin. broad, usually rigid and involute P. repens. 



Not stoloniferous. Leaves more distinct, broader, flat, 

 rather flaccid P. coloratum. 



