20 FLOWERING PLANTS 
CHAPTER Ill 
DISTRIBUTION OF PLANTS 
Ir is impossible thoroughly to understand the vegetation of 
any country without some knowledge of the slowings impor- 
tant facts, which largely determine it : 
1, The position of the country in question with regard to 
a chief climatic zones of the world ; 
2. The climatic changes that ion taken place in past 
geological ages ; 
“73; ‘The changes in the geographical distribution of land and 
water ; 
4, T he influence af man. 
The influence of the above factors on the present distribu- 
tion of plants in Great Britain will now be considered. 
Climatic §§ It will be seen from the accompanying table, 
Zones. which gives a bird’s-eye view of the three main 
climatic zones of the present day with their accompanying 
vegetation and its ecological characteristics, that the vegeta- 
tion of Great Britain must be largely mesophytic. 
ae Amount of _ Character of 
Climatic Zone. - Rainfall. Vegetation, auton. 
1. Tropical. Heavy Dense forests of | Mesophytic 
, Hivergreens fe 
Deficient Desert plants § Xerophytic 
2. Temperate. Poor Desert plants ~- Xerophytic 
Fair and sea- . Grass lands Xerophytic 
sonal 
(Great Britain) Good Open forests of | Mesophytic 
Deciduous trees 
and Conifers 
3, Arctic. Poor. Mosses, lichens,  Xerophytic 
saxifrages 

