18 BULLETIN" 772, 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. Homalocenchbus. 
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. 
lb. 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 which is represented in 
the United States. The only economic species is M elinis minutiftora 
(see p. 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). 
