MR. G. BENTHAM ON GRAMINEA, 79 
in the larger genera there occur occasional exceptions more or 
less decided, which prevent our taking any single one of them as 
an absolute test. The subtribe would inelude the following eight 
genera, in the first five of which the fruiting glume is more or 
less hardened or rigid as in Panicee; in the succeeding three it 
is thinner, though still elosely pressed on the grain. 
1. Aristipa, Linn., is now a genus of at least a hundred 
species, abundant in all the warmer regions of the globe, but also 
represented by a few species in Europe and temperate Asia, and 
by several in North America. With few exceptions it is most 
readily recognized by the long, fine, three-branched awns, the 
lateral branches opposite and spreading.  Doell adds to the 
generic character three lodicules as in Stipa; and Nees describes 
three lodieules in some South-African species; but all other 
Agrostologists describe two only, and I have never found more 
than that number. It is probable that both Nees and Doell 
mistook for the third lodicule the palea, which in many species 
is very thin and scarcely, if at all, larger than the lodieules. The 
genus is divided into tbree fairly marked sections, which Beau- 
vols, Nees, and some others have raised to the rank of genera. 
In (1) Chetaria, Beauv., the flowering glume is continuous with 
the awn without any articulation, and though much longer than 
the empty glumes, and often much attenuated at the end, is 
neither quite awn-like nor decidedly twisted below the branches. 
Amongst its species, Curtopogon was proposed as a genus by 
Beauvois for the North-American A. dichotoma, Mich., in which 
the lateral branches of the awn, instead of diverging from the 
central one, are short and erect at its sides, showing more or less 
distinctly that they are continuations of the lateral nerves of the 
glume. It is probable that this is the case throughout the genus, 
only that the lateral nerves before they diverge are so closely con- 
solidated with the central one as to be undistinguishable from it. 
The genus Ortachne was proposed by Nees for two or three 
Mexican or Columbian plants, originally published by Kunth as 
species of Streptachne, Br., and afterwards transferred by him to 
Aristida, in which the lateral branches of the awn are very short, 
sometimes minute or even quite obsolete, thus nearly connecting 
the section Chetaria of Aristida with the section Aristella of 
Stipa, but in the narrow base of the rhachilla, and some other 
minor points, nearer to the former than to the latter. Ortachne 
retorta, Nees (in Steud. Gram.), is probably a true Stipa. In 
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