IV] 



GRASSLAND ASSOCIATIONS 



183 



Relationships of the Plant Associations of the 

 Siliceous and the Calcareous Soils 



Precisely the same line of reasoning which decides one to 

 place the oak and birch woods in the same plant formation as 

 the scrub and the grassland of the siliceous soils decides one 

 also to place the ash woods and the scrub and the grassland of 

 the calcareous soils in another single formation. 



The parallel relationships of these formations and associa- 

 tions, as developed on the southern Pennines, may be expressed 

 diagrammatically in the following manner : — 



1 Cf. Grisebach's (1846 : 73 and 156, and 1849 : 340—342) usage of the term 

 "plant formation," and also Schimper's (1903 : 161). 



