MR. G. BENTHAM ON GRAMINEZ,. 21 
aid of the admirable *Analyses" in DeCandolle's ‘Flore Fran- 
çaise’ that I was enabled in 1817 and 1818 to learn botany without 
any extraneous teaching; their principle was developed in the 
‘Essay on Nomenclature and Classification’ which I published in 
1823 as a French edition of Jeremy Bentham’s * Chrestomathia,’ 
and I have introduced them more or less into all my local floras. 
lam thus well aware of the great difficulties in the way of draw- 
ing them up satisfactorily, requiring much testing before their 
final revision. They are chiefly useful where all, or nearly all, 
the plants of a country or of a group are well known; and even 
then they frequently require the repetition of the same plant 
under different branches of the key. The best genera and other 
groups are usually distinguished by a combination of characters, 
to each one of which there may be occasional exceptions, and 
these cannot be provided for in any key that presupposes limits 
definitely marked out by single characters. Asa result, there 
are some of Fournier's groups which are evidently good, but to 
which we have no clue but that supplied by the species he includes 
in each. The two genera or subgenera, for instance, into which 
he divides Bouteloua, Lag. (Eutriana, Trin.), are natural and well 
limited; but the only character he gives, the prolongation of the 
rhachis of the spike beyond the last spikelet in the one and not 
in the other, is in fact variable in both groups. Of others, again, 
I ean form no idea of the limits he proposes to assign them. In 
Uniola, for instance, he admits species (unknown to me) which do 
not appear from his description to have what we have been aceus- 
tomed to consider as an essential character of the genus, the four 
to six empty glumes at the base of the spikelet. Where, there- 
fore, I feel obliged to differ from him in the genus to which I 
would refer a species, it may as often be from the inability to 
ascertain what are his views as to the limits of a genus, as from 
that difference of opinion which so frequently prevails amongst the 
best of botanists. 
In recent days, however, we had all been led to look up to my 
much lamented friend the late General Munro as the one who 
was to unravel the intricate web into which the order had become 
involved. His ‘Monograph of Bambuse& ? and various detached 
papers and communications were instalments of great promise; 
he was known to have a thorough acquaintance with species, and 
to have already formed a well-digested framework for genera and 
tribes, an important sample of which he had given in the second 
