10 



POACEAE. 



Racemes disposed in pairs or more : apex of the rachis- 



internodes not appendaged. 



Inflorescence of spike-like silky racemes. 3. ANDROPOGON. 



Inflorescence paniculate. 4. SORGHASTRUM. 



TRIBE III. PANICEAE. 



Spikelets naked, not involucrate. 

 Empty scales 2. 



Spikelets ovate to orbicular, plano-convex, usually 



obtuse, rarely acute. 



Spikelets lanceolate, acute or acuminate. 

 Empty scales 3. 



Empty scales not awned. 



Spikelets in very slender one-sided racemes which 



are usually whorled or approximate. 

 Spikelets in panicles or panicled racemes, the 



latter never whorled, commonly distant. 

 Empty scales awned or awn-pointed. 

 Spikelets involucrate. 



Involucre of numerous bristles. 

 Involucre of two spine-bearing valves. 



TRIBE IV. ORYZEAE. 



Spikelets monoecious : tall reed-like grasses. 

 Spikelets perfect. 



TRIBE V. PHALARIDEAE. 



Third and fourth scales awnless. 



Third and fourth scales awned on the back. 



5. PASPALUM. 



6. SYNTHERISMA. 



6. SYNTHERISMA. 



8. PANICUM. 



7. ECHIXOCHLOA. 



9. CHAETOCHLOA. 

 10. CENCHRUS. 



11. ZlZANIA, 



12. HOMALOCENCHRUS. 



13. PHALARIS. 



14. ANTHOXANTHDM. 



TRIBE VI. AGROSTIDEAE. 



Flowering scale indurated when mature and very closely 

 embracing the grain, or at least firmer than the 

 empty scales. 



Rachilla not extending beyond the palet. 

 Flowering scale 3-awned. 

 Flowering scale 1-awned. 

 Awn twisted. 

 Awn not twisted. 



Flowering scale broad : awn deciduous. 

 Flowering scale narrow : awn persistent. 

 Rachilla extending beyond the palet. 



Flowering scale usually hyaline or membranous at ma- 

 turity, at least more delicate than the empty ones : 

 grain loosely enclosed. 

 Inflorescence a spike. 



Rachilla of the spikelets articulated above the empty 



scales which are therefore persistent. 

 Flowering scale slightly exceeding the empty ones. 

 Flowering scale much shorter than the empty 



ones. 

 Rachilla of the spikelets articulated below the empty 



scales, hence deciduous, entire. 

 Inflorescence an open or spike-like panicle. 



Grain not permanently enclosed in the flowering 

 scale and palet : pericarp opening readily when 

 mature. 

 Grain permanently enclosed in the flowering scale 



and palet : pericarp adherent. 

 Palet 1-nerved and 1-keeled : stamen 1. 

 Palet 2-nerved and 2-keeled : stamens 3. 



Flowering scale with long hairs at the base. 

 Flowering scales naked at the base. 



TRIBE VII. AVENEAE. 



Spikelets readily deciduous as a whole. 



Spikelets with the empty scales persistent, the flowering 



scales deciduous. 



Flowering scale awned below the teeth. 

 Flowers all perfect. 



Grain free, unfurrowed : spikelets less than 1 cm. 



long. 



Flowering scales erose-toothed or shortly 2- 

 lobed at the apex. 



15. ARISTIDA. 



16. STIPA. 



17. ORYZOPSIS. 



18. MUHLENBERGIA. 



19. BRACHYELYTRUM. 



20. HELEOCHLOA. 



21. PHLEUM. 



22. ALOPECDRUS. 



23. SPOROBOLUS. 



24. CINNA. 



25. CALAMAGROSTIS. 



26. AGROSTIS. 



27. NOTHOHOLCUS. 



28. DESCHAMPSIA. 



