2 PLANT GEOGRAPHY 



There Is thus a, vague general recognition of the fact 

 that vegetation varies with latitude and with altitude, 

 accompanied by the inevitable corollary that this dis- 

 tribution of plant life must be largely dependent upon 

 climate. A closer attention to the facts will convince 

 us that, true as this conclusion is, it is by no means the 

 whole truth. If it were so, we might expect, for instance, 

 that distant lands with practically identical climates 

 would bear practically identical vegetation; whereas 

 what we find is, not identity, but a certain resemblance, 

 or, as it is termed, representation. 



Those who own gardens with glass houses, or who are 

 familiar with our large botanical gardens, will recognise 

 in the classification of cultivated plants into such groups 

 as " hardy," " half-hardy/' " greenhouse/' and " stove " 

 plants the same dependence of the life of certain kinds 

 or " species," as the botanist calls them, upon heat, or, 

 at least, upon the exclusion of frost; and will probably 

 also notice that the presence or absence of moisture 

 plays an almost equally important part in their successful 

 cultivation. 



The student of geography soon becomes aware of the 

 vast importance of vegetation in human affairs. Dense 

 forests, % barren deserts, or undrained marshes have 

 always necessarily been thinly peopled. Man, especially 

 in the earlier stages of civilisation, is largely dependent 

 on the crops he can grow in the cleared, drained, and 

 tilled Jand in his immediate neighbourhood. The wild 

 spices he may collect in the forest of the tropics, or 

 the surplus produce of his fields, may be the founda- 

 tion of international commerce. Pasturage for cattle, 

 timber for shipbuilding, or a soil suitable for the growth 

 of some particular plant, whether valuable for food, 

 fibre, medicine, or what not, may largely determine the 

 distribution of population or industries within the 

 individual state. The reckless destruction of some wild 

 species which is a source of wealth may prove the com- 

 mercial ruin of a district; while its careful conservation 

 may mean prolonged economic progress; and the intro- 

 duction of some foreign plant into a region suitable in 

 climate and soil for its cultivation may give a fresh 

 start of prosperity to a land previously but sparsely 

 peopled. 



The intellectual justification of modern botanical 



