16 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 



coriaceous, much firmer than the lemma and palea, the palea some- 

 times obsolete. 



Key to the yenera of Nazieae. 



la. Spikelets single ; first glume wanting 79. OSTERDAMIA. 



Ib. Spikelets in clusters of 2 to 5 ; first glume present 2 



2a. Spikelets bearing hooked spines on the second glume, the group 



forming a little bur 78. NAZIA. 



2b. Spikelets not bearing hooked spines, mostly cleft and awned 3 



3a. Groups of spikelets erect, the spike not one-sided 80. HILABIA. 



3b. Groups of spikelets nodding along one side of the delicate 

 axis 81. AEGOPOGON. 



TRIBE 7, CHLOKIDEAE. 



Spikelets 1 to several flowered, in 2 rows on one side of a con- 

 tinous rachis forming one-sided spikes or spikelike racemes, these 

 solitary, digitate, or racemose along the main axis. 



A large and rather important tribe, confined mostly to warm 

 regions. The group is heterogeneous, the only common character 

 of the genera (aside from the characters that place them in Poatae) 

 being the arrangement of the spikelets in one-sided spikes. Chloris 

 and the allied genera form a coherent group, in which the spikelet 

 consists of one perfect floret and, above this, one or more modified 

 or rudimentary florets. Leptochloa, Eleusine, and their allies, with 

 several-flowered spikelets, are more nearly related to certain genera 

 of Festuceae. The spike is reduced to two or three spikelets or even 

 to one spikelet and is sometimes deciduous from the main axis in 

 Cathestecum and in some species of Bouteloua. In Campulosus 

 there are two sterile florets below the perfect one. 



Key to the genera of Chlorideae. 



la. Plants monoecious or dioecious ; a low stoloniferous perennial- 98. BTJLBIUS. 



Ib. Plants with perfect flowers 2 



2a. Spikelets with more than one perfect floret 3 



3a. Inflorescence a few-flowered head or capitate panicle hidden 

 among the sharp-pointed leaves; a low spreading an- 

 nual 97. MUNBOA. 



3b. Inflorescence exserted 4 



4a. Spikes solitary, the spikelets distant, appressed, sev- 

 eral-flowered 83. TEIPOGON. 



4b. Spikes more than 1 5 



5a. Spikes numerous, slender, racemose on an elongate 



axis 82. LEPTOCHLOA. 



5b. Spikes few, digitate or nearly so 6 



6a. Rachis of spike extending beyond the spike- 

 lets 85. DACTYLOCTENITJM. 



6b. Rachis not prolonged 84. ELEUSINE. 



2b. Spikelets with only 1 perfect floret, often with additional imper- 

 fect florets above__ 7 



