76 MR. G. BENTHAM ON GRAMINE. 
one-nerved, but otherwise the character of Phalaridew is constant. 
They comprise the following six genera :— 
1. EunuARra, Thunb. (Z»ochera, L. C. Rich.), has twenty-four 
species, of which two are from New Zealand, two from the Mascarene 
Islands, and all the rest from South Africa. In them the glumes 
of the second pair are the largest, empty and usually awned, and 
the fertile flower has six stamens. 2. MIcroL£na, Br., including 
Diplax, Hook. f., has five Australian or New-Zealand species, 
differing from Ehrharta only in the number of stamens reduced 
to four or two. 3. TETRARRHENA, Br., four Australian species, 
with four stamens to the flower as in Microlena, but the glumes 
are in less regular pairs, all unawned, and the fourth (one of the 
second pair) alone the largest. The panicle is also almost always 
contracted into a spike, not, however, so dense and cylindrical as 
in the following two genera. 
4. Puaramrs, Linn, has nine or ten extratropical species, 
chiefly from the Mediterranean region, but also extending to 
North and South America. In this genus it is the lowest two 
persistent empty glumes that are the largest, usually very flat, 
and often winged on the keel, the second pair (like the lowest in 
Oryza) very narrow, sometimes reduced to small bristles, those 
of the upper pair thin and hyaline; and sometimes in both of 
them, but almost always in the uppermost one, the central nerve 
is very faint or quite obsolete, a character adduced as an argu- 
ment that this upper one is a two-nerved palea on the floral axis, 
and. not a glume on the main rhachilla. The two nerves are, 
however, very faint, and the central keel is usually marked by a 
line of hairs on the outside, and the question remains a moot one. 
In the majority of species the panicle is contracted into a dense 
globular or cylindrical head; but in P. arundinacea, Linn., a stout 
tall species, forming the genus Digraphis, Trin. (Baldingera, Gertn., 
Meg., and Schrad., T'yphoides, Moench), the inflorescence, though 
still very dense, is more or less branched or interrupted. This 
genus has also been supposed to be distinguished by the want of 
the broad wings of the outer glumes, so conspicuous in the com- 
mon P. canariensis ; but these wings are very narrow in P. para- 
doxa, Linn., and entirely disappear in P. intermedia, Bose (P. 
americana, Ell.), leaving no available characterto separate Digraphis 
generically. 
5. AwTHOXANTHUM, Linn, has four or five European species, 
of which one is now widely spread over various regions of the 
