MR. G. BENTHAM ON GRAMINE Z. 47 
from the pedicels below the spikelets. These sete are not 
epidermal like the rigid hairs of many Gramine&, but, as in 
Pennisetum, are supposed to be abortive branchlets of the 
panicle, differing, however, from those of the latter genus by 
being inserted below the articulation of the pedicel, so as to 
remain persistent after the fall of the spikelet. The species are 
very variable, and a large number have been described as distinct ; 
they appear, however, to be reducible to about ten, three of which 
are common weeds over a great part of the civilized world, and a 
fourth (S. italica) has been much cultivated as one of the Millets 
of the Mediterranean region and the Levant. The genus was 
first fully characterized by Beauvois in his ‘ Agrostographie, 
chiefly from the above-mentioned common weeds; but he had pre- 
viously published and figured, in his Flora of Oware and Benin, 
under the name of Sefaria longiseta, a plant which, as far as I can 
judge without seeing the specimen, proves to be no Setaria at all, 
but the Pennisetum ( Beckeropsis) unisetum, to which I shall pre- 
sently refer. A few species or varieties of Setaria—one, for 
instance, gathered by Hildebrandt in the Sandwich Islands, allied 
to S. viridis, another, not uncommon in the Mexicano-Texan region, 
allied to Š. italica—have, like the variety of S. glauca figured by 
Trinius, t. 195, the lower flower hermaphrodite as well as the upper 
one, which is quite exceptional throughout all genera of Panice& 
except Beckmannia.  Ixophorus, Schlecht. in Linn&a, xxxi. 420, 
was founded as a genus on Urochloa uniseta, Presl, a Mexican 
grass which we do not identify in our collections ; but Trinius 
refers it to Panicum and Fournier to Setaria, with which Schlech- 
tendal’s description agrees very fairly. 
In our second or Cenchrus group of Paniceæ we include four 
genera, chiefly tropical or subtropical, characterized by the 
so-called involuere of bristles surrounding each spikelet or 
sometimes each cluster of two or three spikelets ; this involucre, 
supposed to represent abortive branchlets of the inflorescence, 
being placed above the articulation of the pedicel, always falls 
away with the spikelets; the spikelets themselves are quite those 
of Panicum, the inflorescence usually a simple spike raceme or 
spikelike panicle, rarely a loose panicle of two or more pedunculate 
spikes. 12. CENCHRUS itself, as reduced from the original Linnean 
genus, consists of about a dozen species, both from the New and 
the Old World, two or three of them of very wide geographical 
range, all characterized by the numerous bristles of the involucres 
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