Key to the Genera of the Native and Cultivated Grasses of 



Tennessee. 



The numbers to the right refer to the numbers at the left. The num- 

 bers preceding the names of the genera show their position in sequence. 



I. Spikelets one- rarely two-flowered (when two-flowered the 

 second or terminal flower is perfect, the one below being 

 either staminate or neuter), falling from the pedicels en- 

 tire, singly, in groups, or together with certain joints of 

 the rachis. (Series A. PANICACE^.) 2 



1. Spikelets one- to many flowered, when more than one-flow- 



ered the imperfect flower, if any, is uppermost, rachilla 

 usually articulated above the lower empty glumes so that 

 these remain after the fall of the fruiting glumes. (Ex- 

 ceptions: Alopecurus, Cinna^ Polypogon^ Spartina^ and Holcus.) 

 (Series B. POACE^.) 16 



2. Spikelets terete or flattened on the back 3 



2. Spikelets strongly flattened laterally (Tribe Oryze.e) ... 14 



3. Spikelets all unisexual, plants monoecious (Tribe Mayde.^) 4 

 3 Spikelets hermaphrodite, or staminate and hermaphrodite, 



the former standing near the latter 6 



4. Pistillate and staminate spikelets each in a separate inflor- 



escence, the former axillary, the latter terminal .... 5 



4. Pistillate and staminate spikelets in the same inflorescence, 



the axis of the former articulated between each spikelet. 

 3. Tripsacum. 



5. Pistillate spikes distinct, fasciculate, their axes articulated. 



1. Euchlaena. 



5. Pistillate spikes grown together forming a compound, con- 



tinuous and much thickened axis (the "cob") . . 2. Zea. 



6. Axis of the inflorescence usually articulated, the joints fall- 



ing with the spikelets, flowering glumes more delicate in 

 texture than the outer glumes'. (Tribe Andropogone^.) 7 



6. Axis of the inflorescence continuous, flowering glume indu- 



rated or flrmer in texture than the empty glumes. (Tribe 



PaNICE^,) TO 



7. Spikelets heterogamous; in pairs, one sessile, hermaphrodite; 



one pedicellate, staminate or neuter, or reduced to a plu- 

 mose bristle 7. Andropogon. 



7. Spikelets all alike 8 



8. Spikelets awnless 5. Saccharum. 



8. Spikelets awned 9 



9. Racemes forming abroa(], fan-shaped panicle 4. Miscanthus. 

 9. Racemes upon an elongated main axis forming a much 



branched panicle, branches articulated . 6. Erianthus. 

 10. Glumes (including the flowering) three . 8. Paspalum. 

 10. Glumes four, the lowest usually smaller than the others 



(wanting in Panicum filiforvie) 11 



(8) 



