72 THE TRUE GRASSES. 



4. Only one bristle below each spikelet. 



71. Chamseraphis. 

 NOTE. Compare Pennisetum, Sec. D. 



b. Spikelets in small spikes, these surrounded by 

 large subtending bracts and united into a raceme. 



72. Xerochloa. 



c. Spikelets forming very short spikes which 

 are sunken into cavities of the one-sided, broad 

 axis 73. Stenotaphrum. 



B. Plants monoecious, dioecious, or dichogamous, or the 

 spikelets partly neuter. 



a. Spikes very short, consisting of one $ and two to 

 three upper, neutral spikelets crowded and united 

 into a one-sided spike with a leaf-like axis. 



74. Phyllorachis. 



b. One terminal, simple spike, consisting of one to 

 two lower $ and four to six upper $ spikelets upon 

 a broad (not leaf -like) axis. . . . 75. Thuarea. 



c. Dioacious ; ? spikelets in heads with spiny subtend- 

 ing bracts, $ in spikes which are united into dense, 

 globular heads. . 76. Spinifex. 



d. Mono3cious, spikelets scattered in panicles. 



77. Olyra. 



56. (1) Reimaria Fliigge. Spikelets one-flowered, 

 acuminate-pointed, in loose two-ranked, digitate spikes. 

 Flowering glume and palea slightly indurated. Stamens 

 two. 



Species four, in tropical and sub-tropical America. 

 [One species, R. oligostachya Munro, in Florida.] 



57. (2) Paspalum L. Spikelets one-flowered, usually 

 obtuse, in two- to four-ranked racemes or spikes, these 

 two to many, digitate or disposed in panicles, seldom soli- 

 tary. Flowering glume and palea cartilaginous. Stamens 

 three. 



Species one hundred and sixty, in the tropics of both 

 hemispheres, but most abundant in America, forming an 

 important component of the pampas and campos. 



Sec. I. Eupaspalum. The lower empty glume and 

 the flowering glume turned towards the rachis of the 

 spike or raceme. P. dilatatum (Fig. 24), with remote 

 racemes, is a good forage plant, like many other species of 



