Preface vii 



group is not sufficiently advanced to admit of a grouping 

 of the Mixtae into Natural Families. In dealing 

 with the British Genera alone this arrangement does 

 not appear to do much violence to natural affinities so 

 far as they have been ascertained. 



Among the Flowering Plants Warming's arrange- 

 ment of the Urticales has been followed mainly because 

 of the difficulty of defining the Family Moraceae so as 

 to include Cannabis and Humulus (subfamily Canna- 

 boideae of Engler). 



In all the other Orders the arrangement of the 

 Syllabus has been closely followed, though the actual 

 diagnoses, especially in cases where an Order or Family 

 is poorly represented in Britain, have been to some 

 extent modified. 



The Characters of the Genera have either been ob- 

 tained from various sources, such as Hooker's Students 

 Flora and Garcke's Flora von Detitschlandy or are original, 

 and they will, it is hoped, prove useful to students. 



The following books, besides the Syllabus and 

 Pflanze^ifarniliefiy have been constantly used by me 

 during the compilation of this work. 



Ascherson and Graebner. Flora des NordostdeutscJien 

 Flachlaudes, 1898-9. 



Blytt. Haandbog i Norges Flora, 1906. 



Garcke. Flora von Deutschland. Edited by Dr Franz 

 Niedenzu, 1908. 



«5 



