41 



17. Axis very slender. Spikelets strongly curved 



P. curvatum. 

 Axis stout. Panicle always cylindrical 18 



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



I*, 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 ^-2 ft. by 2-8 tin. 32 



20. Culms very slender ascending from a trailing or rambling- 



base many nodecl, 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 7-0 nerved 22 



Lower valve 5 nerved 25 



22. Lower branches of panicle 3-6 in. long. Pedicels \-i\ 



ins. long P. perlaxum. 



Lower branches of panicle \-2\ ins. long. Pedicels ^-1 

 lin. long ... 23 



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



P. aequinei've. 



Spikelets obtuse, glabrous 24 



2'i. Leaves glabrous. Lower glume not more than i length 



of spikelet P. filiculme. 



Leaves finely hairy. Lower glume \ length of spikelet. 



P. hymeniochilum. 



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



Panicle scanty. Spikelets U-2 lin. long 20 



20. Blades shortly petioled. Longer pedicels up to 1£ lin. 



lung P. ehusqueoides. 



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



P. obumbratum. 



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, blanched base 20 



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

 20. Stoloniferous. Lower leaves distichously imbricate, 1^-3 



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



Xot stoloniferous. Leaves more distinct, broader, flat. 



rather flaccid P. coloratum. 



