THE POLYPODIES. 199 



and in Wales. But from Scotland and Ireland 

 it is almost entirely absent. It is, however, not 

 an uncommon fern in the limestone districts where 

 it grows. 



It is very much hardier in its constitution than 

 the Oak Fern, and will sometimes thrive well 

 when placed on the sunny or exposed part of a 

 rockery, or in the most sunny part of a greenhouse. 

 The soil which suits the other Polypodies will suit 

 Polypodium calcareum. But from its fondness for 

 limestone it will be supposed that the presence of 

 limestone in the soil is desirable. In cultivation, 

 therefore, small pieces of limestone should be 

 mixed with the soil in which it is grown. Like 

 all the Polypodies it has a creeping rhizome, which 

 travels half under the surface of the ground, its 

 matted fibrous roots finding their way into the 

 lower depths of the soil in which it grows, whilst 

 from its upper surface grow the clusters of dark 

 bluish-green fronds. 



