68 THE TRUE GRASSES. 



TRIBE IV. TRISTEGINE.S:. 



Spikelets all $ , 1-2-flowered, in panicled racemes ; 

 axis continuous. Empty glumes three, the third some- 

 times having the function of a flowering glume of a $ 

 flower. Like the preceding tribe, this forms a transition 

 between the Andropogonece and Panicece. All tropical. 



A. Flowering glumes of the Q spikdets aivned ; awns usually 

 geniculate and twisted below. . . . 49. Arundinella. 



B. Flowering glume awnless (frequently, hoivever, the 1-3 

 empty glumes are awned). 



a. First empty glume very small, appressed to the 

 one above 50. Melinis. 



b. First and second empty glumes very small, resem- 

 bling minute scales ; spikelets in spikes. 



55. Beckera! 



c. First empty glume half as large as the second and 

 third, all awnless. 



a. The long racemes of spikelets in distant whorls 

 along a common axis. . . .51. Phaenosperma. 



/?. The short racemes of spikelets solitary along 

 the main axis 52. Triscenia. 



d. First and second empty glume equal in length, 

 half as long as the third and the flowering glume, 

 all awnless ; spikelets minute. . 54. Thysanolsena. 



e. First empty glume subulate, awn- like, projecting 

 beyond the others 53. Arthropogon. 



NOTE. Compare Tricholcena (Panfcw). 



49. (51) Arundinella Eaddi (Ooldbachia Trin., Acra- 

 therum Link, Thysanachne Presl, Brandtia Kunth). (Fig. 

 23.) Spikelets pedicellate, usually in pairs upon the 

 branches of the panicle, pedicels of unequal length. 

 First empty glume shorter than the others, the second 

 frequently awned, the third awnless, usually inclosing 

 a $ flower. 



Species twenty-four, mostly in the tropical regions 

 of the Old World, a few in South America [one in Mex- 

 ico]. 



50. (53) Melinis Beauv. (Tristegis Nees, Suardia 



