24 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Panicles many-flowered, spikelike; glumes well developed, 

 about equal. 

 Panicle short, partly enclosed in the sheath; low annual. 



79. Heleochloa. 

 Panicle elongate; perennial 75. Muhlenbergia. 



TRIBE 6. ZOYSIEAE 



Spikelets subsessile in short spikes of 2 to 5 (single in Zoysia), 

 each spike falling entire from the continuous axis, usually 1 -flowered, 

 all perfect, or perfect and staminate together in the same spike; 

 glumes usually firmer than the lemma and palea, sometimes awned, 

 the lemma awnless. 



This small and unimportant tribe is known also as Nazieae. In 

 Zoysia the spikelets are single and have only one glume, this coriaceous, 

 much firmer than the lemma and palea, the palea sometimes obsolete. 



Key to the genera of Zoysieae 



Spikelets single; first glume wanting 87. Zoysia. 



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



Spikelets bearing hooked spines on the second glume, the group forming a 



little bur 86. Tragus. 



Spikelets not bearing hooked spines, mostly cleft and awned. 



Groups of spikelets erect, the inflorescence not 1-sided 88. Hilaria. 



Groups of spikelets nodding along one side of the delicate axis. 



89. Aegopogon. 

 TRIBE 7. CHLORIDEAE 



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

 rachis, forming 1 -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 Festucoideae) 

 being the arrangement of the spikelets in 1 -sided spikes. Chloris 

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

 consists of 1 perfect floret and, above this, 1 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 2 or 3 spikelets or even to 1 

 spikelet and is sometimes deciduous from the main axis (Cathestecum 

 and Sect. Atheropogon of Bouteloua). In Ctenium there are 2 

 sterile florets below the perfect one. 



Key to the genera of Chlorideae 



Plants monoecious or dioecious. Low stoloniferous perennial- _ 107. Buchloe. 

 Plants with perfect flowers. 



la. Spikelets with more than 1 perfect floret. 



Inflorescence a few-flowered head or capitate panicle hidden among the sharp- 

 pointed leaves. Low spreading annual 106. Munroa. 



Inflorescence exserted. 



Spikes solitary, the spikelets distant, appressed, several-flowered. 



92. Tripogon. 

 Spikes more than 1 (sometimes 1 in depauperate Eleusine). 

 Spikes numerous, slender, racemose on an elongate axis. 



Rachilla and callus of floret glabrous or nearly so; glumes acute, 



less than 5 mm long 90. Leptochloa. 



Rachilla and callus of floret strongly pilose; glumes long-acuminate, 



about 1 cm long 91. Trichoneura. 



Spikes few, digitate or nearly so. 



Rachis of spike extending beyond the spikelets. 



94. Dactyloctenium. 

 Rachis not prolonged 93. Eleusine. 



