l] WHAT IS PLANT GEOGRAPHY? 7 



they may be located, and another (Chapter XVI) on the communities 

 of the oceans and seas. 



Landscapes are often notable for peculiarities which concern the 

 vegetation more than the actual surface of the land, and in Chapter 

 XVII we will consider how landforms, which make up landscapes, 

 tend to be characterized in this way. The study of vegetation, 

 especially of the more established communities, generally gives a 

 better indication of the combined action of environmental factors 

 than all manner of measurements. Consequently the plant geo- 

 graphical and ecological evidence afforded by an area can be of 

 the greatest practical value in interpreting local conditions and in 

 planning the best use of land — particularly for agriculture and 

 afforestation. 



The concluding chapter deals with (i) some natural adaptations 

 and (2) man-made adjustments, both in (a) individual plants and 

 (b) vegetation. This consideration gives us by cross-inference four 

 sets of topics, all of great interest and importance. Examples of 

 these are (ifl) evolution and its mechanisms, (ih) successional 

 change in vegetation, (2«) plant-breeding, and (zb) combating 

 erosion (itself usually brought on by Man's desecration of vegeta- 

 tion). The final paragraphs survey some of the more useful methods 

 of study of plant geography, and give further indication of the 

 values and future possibilities of the subject — both academically and 

 in the service of Man. Despite vast advances in recent decades, 

 there remain whole hosts of unsolved problems ; and, indeed, it is 

 to be questioned whether this last chapter can ever be brought to 

 a satisfactory closure. For such is biological science — an unending 

 frontier. 



Most chapters conclude with some indication, in smaller type, of 

 how further pertinent information may be obtained through recom- 

 mended books which are cited for the purpose. Shorter contribu- 

 tions are ignored in this connection as being too numerous and 

 difficult to select, as well as usually unavailable to the layman, 

 although naturally much of the material presented in this book has 

 been drawn from such specialist ' papers '. 



Geographical Patterns 



The botanical aspects of what may be termed geographical or 

 areal patterns constitute much of plant geography. Such plant- 

 distributional patterns are partly based on physiological reaction to 



