AGROSTIDE^. 193 



There are over 100 species widely spread over the tropical and 

 temperate regions of the New and the Old World. 



The genus is nearly related to Sfipa, though separated from it 

 by having triple awns. 



With few exceptions it is most readily recognized by the long 

 fine three-branched awns, the lateral ones opposite and spreading. 

 The genus is divided into three fairly marked sections, which by 

 some have been raised to the rank of genera. 



1. ArthratJierum (Beauv., as a genus). — Here the awn is decid- 

 edly articulate on the glume, the three consolidated below and much 

 twisted above the articulation below the branches, the floral glume 

 much shorter than the lower empty glumes, instead of exceeding 

 them as in Chmtaria. 



2. CJicetaria (Beauv., as a genus). — The floral glunte is contin- 

 uous with the awn without any articulation, and is neither quite 

 awnlike nor decidedly twisted below the three subequal branches. 

 Amongst its species, Curto^yogo?!, was proposed as a genus, in which 

 the lateral branches of the awn are short and erect. Ortaclme- 

 (Nees, as a genus), Streptachne H. B. K., are two other old generic 

 names. 



3. Stipagrostis (Nees, as a genus). — The awn is articulate on 

 the glume as in Arth rather urn, but scarcely twisted, and above the 

 branches elegantly plumose. Schistachne was once proposed as a 

 genus, in which the central awn above is plumose, the lateral ones 

 short and glabrous. 



Not represented by species in our flora. 



A. Arthratherum. 



a. Floral glume 10 mm. or more in length to the joint. (b) 

 b. Empty glumes 10-15 mm. long, panicle few-flowered. 1 

 b. Empty glumes 15-lT mm. long, panicle larger. . 2 



a. Floral glume 8 mm. or less in length to the joint, the twist- 

 ed beak 15 mm, or more in length (b) 



b. Second empty glume 10 mm. long 'd 



b. Second empty glumes 13-18 mm. long, variety of 3 



B. Chwtaria. 



a. Awns united, solid and twisted at the base, 2 or more cm. 

 loner 4 



