40 



3. Spikelets usually 1 ranked, 2^ lin. long, turgid, very 



obtuse, glabrous P. brizanthum. 



Spikelets 2 (rarely 4) ranked, less than 2^ lin. long 4 



-4. Spikelets turgid, silky villous. Upper hairs in tufts 5 



Spikelets not turgid, nor silky villous. Upper hairs not 



in tufts except in P. marlothii which is 4 ranked 7 



5. Spikelets not constricted at the base, IJ-l^ lin. long. 



P. serratum. 



Spikelets constricted at the base. 2-3 lin. long 6 



■6. Spikelets 2 hn. long P. nigropedatum. 



Spikelets 3 lin. long P. mesocomum. 



7. Spikelets 1 lin. long, finely pubescent 8 



Spikelets more than 1 lin. long, not finely pubescent 9 



8. Spikelets 2 ranked; no tufts of hairs P. isachne. 



Spikelets 4 ranked with minute terminal tufts of hairs. 



P. marlothii. 

 ■9. Fruiting valve smooth. Spikelets loosely white hairy. 



P. glomeratum. 

 Fruiting . valve wrinkled. Spikelets glabrous, or valve 



ciliate along margins 10 



dO. Lower glume with 1-3 bristles from the centre. Lower 

 valve rigidly ciliate along one or both margins ... 



P. trichopus. 

 Spikelets glabrous 11 



11. Fruiting valve mucronate. Lower glume turned away 



from the rachis P. helopus. 



Fruiting valve not mucronate. Lower glume facing the 

 rachis P. arrectum. 



12. Ligule 13 



Ligule a fringe of hairs 14 



13. Culms stout terete. False spikes compound in dense 



panicles P. crus-pavonis. 



Culms and sheaths compound below. False spikes simple 

 or sub-simple P. criis-galli. 



14. False spikes erect. Glumes and lower valve woolly 



ciliate P. holubii. 



False spikes oblique or spreading. Glumes and valve 

 not woolly ciliate 15 



15. False spikes sohtary, usually awned P. stagninum. 



False spikes fascicled or crowded, shortly cuspidate. 



P. pyramidale. 



16. Panicle cylindrical or if sometimes open (P. curvatum) 



then the spikelets strongly curved 17 



Panicle loose or effuse J9 



