INTRODUCTION 



well-known trees as the White Ream, Wayfaring Tree, Box, and Purging 



Buckthorn. 



The list of flowering shrubs, deciduous trees, and conifers which may 

 be planted on a chalk soil is a long one indeed, and many of these will 

 flourish where the layer of soil resting on the chalk is often not more 

 than six inches deep. 



INFLUENCE OF TREES UPON SOIL 



We have written at some length as to the influence of soil upon the 

 growth of trees, but we may also note that the converse of this is true, 

 namely, that trees largely influence the composition of soils in providing 

 that humus which is so necessary for vegetable growth. It has been 

 estimated "that after a sandy soil in New England is so exhausted that 

 it will produce nothing but red mosses, it may be renewed to its pristine 

 vigour and productiveness by the growth of trees on it for thirty years." 



METHODS OF ROOTING 



Trees and shrubs vary considerably in their method of rooting, for while 

 the Ash, Birch, Cedar of Lebanon, Horse Chestnut, Oak, and Plane are 

 inclined to root deeply, others, as the Beech, Elm, Lime, and Sycamore, often 

 ramify so near to the surface as to kill plants growing near them, and 

 frequently make it difficult or impossible for even grass to grow beneath 

 their shade. 



SITUATION AND ITS INFLUENCE 



Not only does the soil decide the fate of trees and shrubs, but the 



question of sunshine or shade, exposure or shelter, are important factors 



in their life-history. Many will thrive best when able to bask in sunshine, 



as the Satin Flower and Golden Bell, while others delight in shade, as 



the Tutsan and Large-flowered St. John's Wort. 



Many evergreens will do well under the shade of trees, among them 



iv 





