AGROSTIDEjE 221 



3 i . Aristida, L. 



These are tufted, annual or perennial grasses. Spikelets are 

 panicled, I-flowered, laterally compressed, with the rachilla 

 jointed above the empty glumes, 3-glumed. The first and the 

 second glumes are narrow, keeled, I-nerved, awned or not and 

 persistent. The third glume is very narrow, cylindric, coriaceous 

 convolute, acuminate, 3-nerved, tip produced into a long 3-partite 

 naked or hairy awn twisted below the branches, with a minute 

 palea which is convolute round the ovary. Lodicules are two, 

 linear or oblong-linear and hyaline. Stamens are three. Styles 

 are distinct. Grain is long, narrow and cylindrical. 



KEY TO THE SPECIES. 



Awn tripartite from the base and not articulate with the top of 

 the glume, persistent and glabrous. 

 Annual. 



Glumes I and II not awned. 



Awn without anv column and branched I 1. A. Adscensci- 



from the base. J on is. 



Awn with a short column and with \ 



shorter branches. J 4- A. mutabilis. 



Perennial. 



Panicle cylindric, glumes I and II) . 



awned ; callus with white silky hairs. J 2 " A- setace a. 



Panicle effuse, glumes I and II awned \ . a H st ' 

 or not ; callus naked. / 1X * 



Awn with a long column, tripartite at the top. 



Annual ; panicle lax, narrow ; glumes II c a funiculata 

 and II awned. j 



