xvi INTRODUCTION 



the orders Umbelliferae and Compositae, and in the genera 

 Saxi/raga, Achillea, Euphrasia, and Car ex, a full de- 

 scription of the minute differences between the species 

 would have extended the work to an unwieldy size. 

 The common practice of systematists of giving a clavis 

 of the genera in each order and of the species in each 

 genus has been discarded, because this frequently results 

 necessarily in naming only a single character by which 

 species may be distinguished, to the omission of others 

 much more useful to the unpractised botanist. In all 

 the larger genera the species are first of all classified into 

 a number of groups, some conspicuous character being 

 used, such as the colour of the flower, or the arrange- 

 ment of the flowers or leaves, which does not necessarily 

 imply genetic affinity, and which therefore often separates 

 species which would be placed near to one another in a 

 more scientific flora. We may give as an example of 

 this Anemone sulphurea, which is undoubtedly nearly 

 allied to A. alpina, the former being found on the grani- 

 tic, the latter on the calcareous Alps; and yet they are 

 placed in different sections owing to the difference in the 

 colour of their flowers. 



With regard to the cultivation of alpine plants in 

 our gardens and rockeries, it must always be borne in 

 mind that their chief enemy in our climate is not cold, 

 but excessive moisture in the winter, from which they 

 are protected in their native country by the friendly 

 covering of snow. As to practical details, we cannot 

 do better than quote the substance of the instructions 

 given by Graf in his Introduction to Seboth's " Alpine 

 Plants": 



"The great object of the cultivation of alpine plants 



