44 ME. G. BENTHAM ON GBAMIIfE^. 



Oplismenus ; but the development of the awn has now been shown 

 to be so frequently uncertain in one and the same species of 

 Graminese, that the character has quite lost the absolute import- 

 ance once attributed to it by Beauvois and others, and JEchinocJiloa 

 is generally admitted only as a slightly distinct section of Panicmn. 

 The true Oplismenus may, however, be well maintained as a sepa- 

 rate genus, to which I shall presently refer. 



(8) Ptychophyllum has been well worked up as a very distinct 

 section of Panicum by A. Braun. It comprises P. plicatum, Lam., 

 from the Old World, P. sulcatum, Aubl., from America, and a 

 few others, which, with a peculiar foliage, have more or less of 

 setsB in the panicle, which seem to connect them with Setaria. 

 On examination, however, these setae will be found in PtycJiopTiyl- 

 lum to be merely the setiform tips of the ultimate spikelet-beariiig 

 branches of the panicle, whilst the bristles or setae of Setaria are 

 abortive branchlets, forming a kind of involucre below the spike- 

 lets. The remaining floral characters o{ PiycJiophyllwn are entirely 

 those of the loosely-panicled species of Uupanicmn. 



(9) Symenacline of Beauvois, often retained wholly or partially 

 as a genus, comprises a small number of species both from the 

 New and the Old "World, in which the small, very numerous 

 spikelets are usually crowded in a long narrow cylindrical spike- 

 like panicle. In the typical species, P. myurus, Linn., the spike- 

 lets are rather acuminate and the fruiting glume scarcely hardens ; 

 in P. indicum, Linn., and others the spikelets are small, and 

 quite those of a large number of true Panica. 



(10) Eupaniomn. After deducting the nine preceding sections 

 and the succeeding Tricholoena, which have all some distinguishing 

 peculiarity, there remain a large number of sjjecies strictly normal 

 in the structure of their awnless spikelets, and connected together 

 by their more or less spreading panicle, the Bj)ikelets, on short 

 or on slender pedicels, clustered or scattered along its simple or 

 divided branches. These species, in number not far from two 

 hundred, may vary much in the size of the spikelets, in the degree 

 of development of the panicle, and in other minor points, but 

 seem little capable of being classed in distinct subsections. They 

 form Trinius's two sections Virgaria and Miliaria, characterized 

 by the branches of the panicle being angular in the one, terete in 

 the other — a distinction which I have been quite unable to follow 

 out, at least in the dried specimens. All I have been able to 

 suggest has been their distribution into seven groups or series 



