12 



GRAMINEAE 



Flowers perfect, staminate or wanting. 

 Spikelets much flattened laterally. 

 Spikelets not much flattened laterally. 

 Flowering glume with a short hooked 



awn. 



Flowering glume long awned. 



Inflorescence spike-like. 



Flowers long-silky. 



Flowers not silky. 



Inflorescence panicled. 



Flower with two plumose pedicels 



at base. 

 Flower without plumose pedicels 

 at base. 

 Flowering glnme not awned. 

 Flowers in open panicles. 

 Flowers in spikes. 

 Spikelets subtended by an invo- 

 lucre. 

 Involucre spiny. 

 Involucre consisting of bristles. 

 Spikelets not subtended by an in- 

 volucre. 

 I^chis produced beyond upper- 

 most spikelet. 

 Rachis wider than spikes. 

 Kachis not wider than spikes. 

 Rachis not produced beyond up- 

 permost spikelet. 

 Spikelets obovate, Avith cari- 



nate glumes. 

 Spikelets plano-convex, not 

 carinate. 

 Spikelets obtuse. 

 Spikelets acute. 

 Spikes digitate at top of 



culm. 

 Spikes not digitate. 



12. HOMALOCENCHRUS. 



27. HoLcus. 



2. Andropogon. 

 8. Panicum. 



3. sorghastrum. 



4. Sorghum. 

 8. Panicum. 



10. Cenchrus. 

 9. Chaetochloa. 



5. Paspalum. 

 30. Spartina. 



33. Beckmannia. 

 5. Paspalum. 



7. Syntherisma. 

 6. Eriochloa. 



II. 



Spikelets l-many-flowered. Rachis articu- 

 lated above the two lower glumes, so 

 that they remain when the flower breaks 

 off. 



Spikelets not arranged in rows. 

 Spikelets with one perfect flower. 

 Spikelets with two or more perfect flow- 

 ers. 



Spikelets in two rows in one-sided spikes. 



Spikelets in two rows on opposite sides of 

 a spike. 



A. 



Flowers three-awned. 

 Flowers awnle.ss or one-awned. 

 Panicle open, not spike-like. 



B. 

 C. 



D. 



15. Aristida. 



