103 



Tribe 2.— MAYDEJS. 



Spikelets unisexual ; the male flowers terminal, spicate or panicu- 

 late ; the female ones below, spicate, disarticulating (except in Zea) 

 with the joints of the rhachis. 



Genera: 1. Coix ; 2. Tripsacum. 



Tribe 3.— ORYZE^E. 



Spikelets perfect, or rarely unisexual, paniculate or spicate. Outer 

 glumes usually minute or absent, the flower apparently inclosed by 

 two one-nerved glumes, the upper of which is generally considered a 

 palet. 



Genera: 1. Hydrochloa; 2. Luziola ; 3. Zizania; 4. Leersia. 



Tribe 4.— TRISTEGINE^E. 



Spikelets perfect, paniculate or sparsely fasciculate. Glumes three 



or four, the two or three inferior ones empty, membranaceous ; 



the terminal or flowering one awnless or often terminated with a 



geniculate awn, and with a hyaline or thinly membranaceous palet. 



Genera : 1. Thurberia. 



Tribe 5.— ZOYSIE^E. 



Spikelets usually perfect, or some of them imperfect, articulated 

 singly or in fascicles with the inarticulate rhachis of the simple spike ; 

 flowering glumes membranaceous ; generally the outer or empty ones 

 smaller and hyaline. 



Genera: 1. Hilaria ; 2." JEgopogon ; 3. Oathestechum ; 4. 

 Tragus. 



Tribe 6.— ANDROPOGONEJL 



Spikelets arranged along the rhachis of the spike or the branches 



of the panicle most commonly in twos, or the terminal ones in threes, 



homogamous or heterogamons in every pair. Flowering glume 



smaller than the empty ones, hyaline, often bearded. 



Group 1. — Spikelets spicate, awnless, generally in pairs, in alternate 



notches of the generally articulate rhachis, one, rarely 2, 



sessile and fertile, more or less imbedded in the excavation 



of the rhachis, one pedicelled and sterile. 



