MALE FERN AND ITS RELATIVES 65 



dom. The species has a slender creeping under- 

 ground stem from which arise the delicate fronds. 

 These are usually about four to eight inches in 

 length, and the stipes is considerably longer 

 than the leafy portion. The design of the frond 

 is rather like that of the three-branched Poly- 

 pody, this being due to the fact that the lowest 

 pair of pinnae is much larger than any of the 

 others. 



The general outline of the fronds is wedge- 

 shaped, and these are very finely divided. 

 Indeed in a well-developed leaf the fronds may 

 be three or even four times pinnate. The pin- 

 nules themselves are also deeply cut. It will 

 be noticed that the lower portion of the frond is 

 always more freely divided than the upper part ; 

 a common characteristic in Ferns. 



The sori are very freely scattered on the lobes 

 or pinnules at the back of the frond, and these 

 are covered with the curious hooded indusia 

 which were noticed in the last species. 



The Mountain Bladder Fern is perhaps the 

 rarest of all our native species. It is at home 

 in mountainous districts, and seems only to have 

 been noticed in a few localities in Wales and 

 Scotland. Probably it would be seen more 

 often were it not that it grows in positions which 

 are not of easy acces >. It should be given the 

 same treatment in the garden as that recom- 

 mended for the Brittle Bladder Fern. The 

 fronds disappear in the winter. 



In some books a species is given, known as 

 Cystopteris alpina or regia. The plant nearly 

 resembles Cystopteris fragilis, although it is 

 somewhat smaller. This is a very doubtful 

 native, as it seems only to have been recorded 

 in one or two localities where it may have been 

 naturalized. 



