18 BULLETIN 112, U. S. DEPARTMENT OF AGRICULTURE. 



TRIBE 9, ORYZEAE. 



Spikelets 1-flowered, perfect, strongly laterally compressed, panic- 

 ulate ; glumes reduced or wanting ; palea apparently 1-nerved ; stam- 

 ens 6. 



A small tribe whose affinities are not evident. It includes rice, the 

 important food plant. 



- Key to the genera of Oryzeae. 



Glumes minute; lemma often awned 102. ORYZA. 



Glumes wanting; lemma awnless 103. HOMALOCENCHRUS. 



TRIBE 10, ZIZANIEAE. 



Spikelets unisexual, the pistillate terete or nearly so; glumes 

 shorter than the lemma, usually one or both obsolete, the pedicel dis- 

 articulating below the spikelet. 



A small tribe of uncertain affinities; the species aquatic or sub- 

 aquatic, of no economic importance except the Indian rice (Zizania). 



Key to the genera of Zizanieae. 



la. Culms slender ; plants low ; staminate and pistillate spikelets borne in 



separate inflorescences 2 



2a. Inflorescence a few-flowered spike ; plants not stoloniferous. 



107. HYDROCHLOA. 



2b. Inflorescence a panicle; plants stoloniferous 106. LUZIOLA. 



Ib. Culms robust ; plants tall ; staminate and pistillate spikelets borne in 



the same panicle - 3 



3a. Plants annual; pistillate spikelets on the ascending upper 

 branches, the staminate on the spreading lower branches of the 



panicle '. 105. ZIZANIA. 



3b. Plants perennial; pistillate spikelets at the ends, the staminate 



below on the same branches of the panicle 104. ZIZANIOPSIS. 



TRIBE 11, MELINIDEAE. 



Spikelets disarticulating below the glumes, these very unequal, the 

 first minute, the second and the sterile lemma equal, membranaceous, 

 strongly nerved, the latter bearing a slender awn from the notched 

 summit ; fertile lemma and palea thinner in texture, awnless. 



A tribe of about a dozen genera, none of w r hich is represented in 

 the United States. The only economic species is Melinis minutiftora 

 (seep. 212). 



TRIBE 12, PANICEAE. 



Spikelets with one perfect terminal floret and below this a sterile 

 floret and two glumes; fertile lemma and palea indurate or at least 

 firmer than the glumes and sterile lemma; articulation below the 

 spikelet. 



A large tribe, confined mostly to warm regions, and containing few 

 economic species. The first glume is wanting in some genera, such 

 as Paspalum, and rarely the second glume also (Eeimarochloa). 



