80 MR. G. BENTHAM ON GRAMINE 2. 
(2) Arthratherum, Nees, the awn is decidediy articulate on the 
glume and much twisted above the articulation below the branches, 
the flowering glume itself much shorter than the lower empty 
glumes, instead of exceeding them as in Chetaria. In (3) Sti- 
pagrostis, Nees, the awn is articulate on the glume, as in Arthra- 
#herum, but scarcely twisted, and above the branches elegantly 
plumose, the branches also being plumose in some species ; whilst 
in others, forming Figari and De Notaris's proposed genus Schis- 
tachne, the central awn alone is plumose, the lateral branches 
short and glabrous. All, however, are most conveniently in- 
cluded in the great genus Aristida. 
2. Srrpa, Linn., is almost as numerous and as widely spread 
as Aristida. It is also strongly characterized, as to the great 
majority of species, by the narrow, rather hard fruiting glume, 
earrying off a rather long or obconical internode of the rhachilla 
(or so-called callus), by the long undivided awn more or less 
articulate on the glume aud usually twisted at the base, and by 
the presence of three lodicules ; but the exceptions to one or more 
of these characters are more numerous than in Aristida; the in- 
ternode of the rhachilla varies much in length and in shape, the 
articulation and twist of the awn gradually disappear in some 
species, and the third lodicule, though often as large as the others, 
is sometimes much smaller or even quite obsolete. The genus is 
also not so clearly divisible into sections as Aristida, although 
several genera have been proposed for more or less aberrant 
species. Macrochloa, Kunth, includes S. tenacissima, Linn., and 
S. arenaria, Brot., both from the Mediterranean region, remark- 
able for their large membranous glumes, the flowering one shortly 
bifid at the apex. In dristella, Bertol., founded on S. aristella, 
Linn., a European and Mediterranean species, in Streptachne, Br., 
a single Australian species, and in Orthoraphium, Nees, two or 
perhaps three East-Indian species, the flowering glume is 2-toothed 
or shortly bifid at the apex, the awn scarcely or not at all articu- 
late, and the internode of the rhachilla very short, though still 
perhaps slightly thickened under the flowering glume. The 
S. aristella, however, is very closely connected with typical Stipe 
through S. sibirica, Lam., S. Redowskii, Trin., and S. altaica, 
Ledeb. Jarava, Ruiz and Pav., was founded on S. jarava, Kunth 
(S. eriostachys, Cav., S. papposa, Nees), a widely-spread West- 
American species, to which the small spikelets in a long narrow 
dense panicle, with the flowering glumes crowned under the awn 
