50 



POACEAE 



TRIBE II. ANDROPOGONEAE. 



A. Internodes of the rachis not thickened nor excavated for the reception of 



the spikelets. 

 Spikelets alike, perfect. 



Axis of the racemes continuous, not articulated. 2. IMPERATA. 



Axis of the racemes articulated. 3. ERIANTHUS. 



Spikelets not alike : 



All pedicellate, the long-pedicellate one perfect, the short-pedicellate one 



staminate. 6. TRACHYPOGON. 



Sessile and pedicellate, the former perfect, the latter empty, staminate 



or wanting. 



First empty scale of the sessile spikelet balsam-bearing. 7. ELIONURUS. 



First empty scale of the spikelet not balsam -bearing. 



a. Sessile spikelets alike throughout the inflorescence. 

 Racemes singly disposed : apex of the rachis-internodes a trans- 

 lucent cup-shaped, entire or irregularly toothed, appendage. 8. SCHIZACH YRIUM. 



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

 nodes not appendaged. 

 Rachis-internodes and pedicels sulcate, the median portion 



translucent, the margins thickened. 10. AMPHILOPSIS. 



Rachis-internodes and pedicels not sulcate. 



Some or all of the racemes sessile. 9. ANDROPOGON. 



All of the racemes more or less pedunculate. 

 Sessile spikelets dorsally compressed. 



Pedicellate spikelets wanting. 12. SORGHASTRUM. 



Pedicellate spikelets present and usually staminate. 11. SORGHUM. 

 Sessile spikelets rounded or laterally compressed. 



Racemes with many internodes : awns none. 13. VETIVERIA. 



Racemes with usually but one internode : awns long. 14. RAPHIS. 



b. Lower spikelets differing from the others. 15. HETEROPOGON. 



B, Internodes of the rachis much thickened and excavated to receive the 



spikelets. 



First scale of the spikelet flat or convex. 4. MANISURIS. 



First scale of the spikelet globose. 5. HACKELOCHLOA. 



TRIBE III. ZOYSIEAE. 



Second empty scale naked. 16. HILARIA. 



Second empty scale with hooked spines on the back. 17. NAZIA. 



TRIBE IV. TRISTEGINEAE. 

 Inflorescence a panicle, the spikelets long-awned. 



TRIBE V. PANICEAE. 

 A. Spikelets all perfect. 



a. Spikelets not sunken in the rachis. 

 1. Spikelets nnked, not iiivolucrate. 

 Empty scale 1. 

 Empty scales more than 1. 

 Empty scales 2. 



Lower empty scale with a thickened ring-like callus. 

 Lower empty scale unappendaged. 



Spikelets in one-sided racemes or spikes. 



Flowering scale with its opening turned from the rachis. 

 Spikelets ovate to orbicular, usually obtuse, rarely acute. 

 Spikelets lanceolate, acute to acuminate. 

 Flowering scale with its opening turned toward the rachis. 

 Spikelets in panicles : 

 Fertile. 



Sterile : fertile spikelets on short subterranean branches. 

 Empty scales 3. 



Palet of the third scale not enlarged. 



Second empty scale not saccate at the base. 



Spikelets acute to obtuse, their empty scales not markedly 

 exceeding the flowering ones. 

 Spikelets sessile or nearly so, singly disposed : flowering 



scale with the opening toward the rachis. 

 Spikelets more or less distinctly pedicellate, usually in 

 pairs or more ', flowering scale with the opening 

 turned from the rachis. 

 Empty scales not awned. 



Spikelets in very slender one-sided racemes which 



are usually whorled or approximate. 

 Spikelets in panicles or panicled racemes, the lat- 

 ter never whorled, commonly distant. 

 Spikelets lanceolate, acuminate, long-hairy. 

 Spikelets orbicular or lanceolate, if the latter 



then glabrous. 



Spikelets in pairs in one-sided racemes : first 

 scale of the short-pedicelled spikelet 

 turned to one side and often much 

 longer than the corresponding scale in 

 the other spikelet. 



Spikelets not in one-sided racemes, or if thus 

 arranged, the first scale of the spikelets 

 central. 



18. LlMNODEA. 



19. REIMARIA. 

 25. ERIOCHLOA. 



20. PASPALUM. 

 27. SYNTHERISMA. 



22. ANASTROPHUS. 



23. ANTHAENANTIA. 



24. AMPHICARPON. 



26. BRACHIARIA. 



27. SYNTHERISMA. 



28. TRICHACHNE. 



21. DlMORPHOSTACHYS. 



31. PANICUM. 



