INTRODUCTION 



In this volume are included the remaining British species not described in 

 Vols. II-V. They are also arranged in systematic order under each section based 

 on broad ecological lines. To assist in the identification of plants in this and 

 preceding volumes, a summary, first, of the natural orders and, secondly, of the 

 genera is given in Vol. V. But, the work not being primarily intended to define 

 the systematic characters of plants, reference to a work with analytical keys, 

 such as Bentham and Hooker, may be made for that purpose. In the introduc- 

 tion to this volume some remarks are appended upon : 



(a) The composition of the British flora. 



(b) Status of some Britannic plants. 



(c) Some further notes on species and varieties. 



(d) Hybrids. 



(e) Identification of species. 



(f) Nomenclature. 



The composition of the British Flora, as at present understood, may be best 

 gathered by a study of Mr. Druce's British Plant List, which is very compre- 

 hensive, so that there is no danger of erring on the side of under-estimation. 



In this list are included 2958 flowering plants, excluding Gymnosperms and 

 Cryptogams. Since it was published many more have since been added. 1 



Of native or well-established species there are some 1759. These, includ- 

 ing some Gymnosperms and Cryptogams not embraced in that number, are made 

 up as follows : 



Native species ... ... ... ... ... 1390 



Sub-species ... ... ... ... ... ... 401 



Species doubtfully native ... ... ... ... 89 



1880 



Alien species now well established ... ... 144 



Aliens more or less fugitive... ... ... ... 940 



This includes 5 extinct species and 5 others doubtful. There are 1430 varieties 

 and 259 hybrids, over and above 23 not included in these numbers. 



Of the aliens 751 are natives of Europe, 

 102 ,, ,, Asia, 



23 ,, ,, Africa, 



162 ,, ,, America, 



6 ,, ,, Australasia, 



30 are cultivated (in many cases natives of Asia and Africa). 



1 See Adventive Flora of Tweedside and Mr. Druce's Alien Flora. 

 vii 



