ME. G. BENTnAM ON GBAMINEJE. 21 



aid of the admirable "Analyses " ia DeCandoUe's 'Flore Fran- 

 §aise ' 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. 

 I am 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. As a 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 Souteloua, Lag. {Hutriana, 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 can 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 accus- 

 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 

 woidd 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 atpongst 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 Bambusese ' 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 



