VI PREFACE. 



but when few are known out of many presumed to exist, it is 

 impossible to say which may be the diagnostic characters of a 

 species and which common to others of the genus. 



The ' Flora of Tropical Africa,' forming one of the series of 

 Floras undertaken, at the instance of the late Sir William J. Hooker, 

 under the authority of the Home or of Colonial Governments, it 

 is necessarily uniform in general plan with those which have been 

 already issued. 



The principal features of this plan, as settled by Sir W. J. 

 Hooker, and described in his report,* are these : — 



1st. The descriptions are drawn up in the English language. 



2nd. The general sequence of Natural Orders adopted is that 

 of the ' Prodromus ' of De Candolle, being that which experience 

 has shown to be practically the most convenient. In accordance 

 with this sequence, British Botanists are accustomed to arrange 

 their Herbaria and works of descriptive Botany. In the more 

 detailed arrangement of the genera, the ' Genera Plant arum ' of 

 Messrs. Bentham and Hooker has been followed, and a reference 

 to that work is given with each genus. 



With regard to the synonymy of the species here described, 

 while the authors have endeavoured to quote all names which have 

 been appUed to tropical African plants, they have not, in the case 

 of widely difiPused species, regarded it as either necessary or desir- 

 able to include their whole synonymy, the reliable citation of 

 which would have involved very much more time, labour, and 

 space than the end to be attained would warrant, besides that it 

 would be out of place in a special work of this kind. Any new 

 identifications of African with extra-African species are of course 

 recorded. 



Those who are unaccustomed to the use of works of descriptive 

 Botany in the field, it may be well to caution in respect of the 

 dimensions of the various organs given throughout the work in 

 English feet, inches, and lines {j\ inch). The extremes quoted 

 are simply intended to include the usual or average range of size 

 * See ' Natural History Review,' 1861, p. 255. 



