152 



VEGETATION OF THE PEAK DISTRICT 



[CH. 



Swamps are much less numerous in the limestone tract 

 than on the less porous sandstones and shales. Most of the 

 swamps in the limestone area occur at the bottoms of the 

 dales, although a few occur on the grassy slopes, wherever 

 springs issue through the soil. A very large number of species 

 which characterize the swamps of the sandstone and shale are 

 absent from those of the limestone, whilst some species are 

 restricted to the limestone swamps. The following species 

 have been found in the limestone swamps of north Derbyshire ; 

 and it will be seen that the total floristic composition of the 

 limestone swamps is very different from that of the sandstone 

 swamps, just as the soluble mineral content of each is very 

 different. These differences are sufficiently important to justify 

 the placing of the two kinds of swamps in separate plant 

 formations. 



In similar limestone swamps of the mid-Pennines, the bird's 

 eye primrose (Primula farinosa) is abundant, and there reaches 

 its southern British limit. 



Admitting that the two kinds of swamps should be placed 

 in separate plant formations, the question arises as to which 



