PREFACE. vii 



important characters of the plant ; finding, moreover, from experience, 

 that such keys promote very superficial habits amongst students. 



For the areas and elevations inhabited by the Species in the British 

 Isles I am wholly indebted to Mr. Watson's accurate works, and espe- 

 cially to his (unfortunately unpublished) " Compendium of the Cybele 

 Britannica," 1868-9. The limits of the more or less local Species are here 

 defined by the counties, and the addition of northwards or southwards 

 indicates that they extend to Caithness and Sutherland, and to Cornwall 

 and Kent, respectively. When a plant is remarkable for its absence in 

 Ireland, this is stated ; and when rare or local in Ireland, its limits are 

 taken from the "Cybele Hibernica" of More and Moore, a standard 

 work. Of the altitudes, I have chosen the highest the Species attains, 

 and indicated the region where this is the case ; where no elevation is 

 given, the Species is not known to ascend to 1,000 feet, and may be 

 assumed to be a " low-ground" plant. To the doubtfully indigenous 

 Species I have added Watson's opinion as to whether they are " colonists " 

 or "denizens," &c. The extra-British distributions I had worked out 

 myself for most of the British plants before the appearance of Mr. Wat- 

 son's " Compendium ; " I have, however, revised them by means of the 

 latter work with great advantage. 



The estimates of the numbers of Genera in the Orders, and of Species 

 in the Genera, are compiled from the Kew Herbarium, and from many 

 other sources, and are unavoidably very vague ; they serve to indicate to 

 the student the relative extent of these groups. The notices of their 

 affinities and properties are necessarily extremely brief indications. The 

 etymologies I have endeavoured to reduce to really useful limits. Only 

 such English names as are pretty well known are given, and for these I 

 have in many cases been guided by Dr. Alexander-Prior's " Popular 

 Names of British Plants," a very good book. 



I am greatly obliged to Mr. J. G. Baker for an account of the Genera 

 Rubus, Rosa, and Hieracium, and wish that I had enlisted his services 

 for the aquatic Ranunculi, of which I have admitted too many Sub-species. 



