44 MR. G. BENTHAM ON GRAMINEX. 
Oplismenus ; but the development of the awn has now been shown 
to be so frequently uncertain in one and the same species of 
Graminee, that the character has quite lost the absolute import- 
ance once attributed to it by Beauvois and others, and Echinochloa 
is generally admitted only as a slightly distinct section of Panicum. 
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 distinet 
section of Panicumby A. Braun. It comprises P. plicatum, Lam., 
from the Old World, P. sulcatum, Aubl. from America, and a 
few others, which, with a peculiar eus have more or less of 
sete in Te panicle, which seem to connect them with Setaria. 
On examination, however, these sete will be found in Ptychophyl- 
lum to be merely the setiform tips of the ultimate spikelet-bearing 
branches of the panicle, whilst the bristles or sete of Setaria are 
abortive branchlets, forming a kind of involucre below the spike- 
lets. The remaining floral characters of Ptychophyllum are entirely 
those of the loosely-panicled species of Eupanicum. 
(9) Hymenachne 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 seri hardens; 
in P. indicum, Linn., and others the spikelets are small, and 
quite those of a large number of true Panica. 
(10) Eupanicum. After deducting the nine preceding sections 
and the succeeding Tricholena, which have all some distinguishing 
peculiarity, there remain a large number of species strictly normal 
in the structure of their awnless spikelets, and connected together 
by their more or less spreading panicle, the spikelets, on short 
or on slender pedicels, elustered 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 distinet subsections. They 
form Trinius's two sections Vi Virgaria and Miliaria, characterized 
by the branches of the panicle | being angular i 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, 
