CHAPTER II. 



Plant Distribution and Associations. 



5EFORE passing to the consideration of the distribution 

 of plants within the limits of the parish, it is desirable to 

 enquire shortly where they come from, and to show that they 

 have not all the same history, nor geographical range. To 

 begin with, all our native plants occur not only elsewhere in 

 England, but also on the continent; and it is from Europe, 

 almost exclusively, that this country has received both its flora 

 and fauna by successive immigrations, which, however, have 

 not necessarily originated in the same quarter. Every species 

 occupies a definite area, which may be almost world-wide, or 

 may be a single small island. It may at any time be gradually 

 gaining or losing ground ; and it is usually most abundant at 

 the centre, and diminishes towards the boundaries of this area. 

 These plant areas overlap without coinciding, and produce 

 endless combinations of species from place to place, the kaleido- 

 scopic effect of which, in any district, is reflected in its local 

 Flora ; but it is also the function of such a work to analyse the 

 elements of the picture, and determine the local combina- 

 tions. 



On examining the range of our plants outside Britain, it is 

 possible to discover wide differences in the areas they 



occupy, and to group together plants of similar 

 Continental range, whereby they are reduced to a small 

 Range. number of classes, the members of each class 



having, undoubtedly, had a somewhat similar 

 history and origin. The classes here adopted as the most 

 convenient are as follows : — 



(i.) Cosmopolitan species, which are found nearly all over 

 the world, or at least, in all the continents. It is a very small 

 class, of which the dandelion, yarrow, silver-weed, bracken, 

 convolvulus and duck- weed will serve as examples. In part it 



