98 WHERE TO FIND FERNS. 



XXVII. THE MOUNTAIN BLADDER FERN. 



Cystopteris montani. 

 (Plate X., Fig. 3, page 67.) 



LENGTH OF FROND. Four to ten inches. 



GENERAL DESCRIPTION. Roots fibrous, not very 

 abundant. Rootstock, a rhizoma, which creeps consider- 

 ably in a horizontal direction, thin and dark-coloured. 

 Fronds abundant, bright green, brittle, herbaceous, 

 produced from numerous points along the rhizoma ; 

 stipes about twice the length of the leafy part, which is 

 somewhat triangular in general form and tripinnate in 

 its lower part, though bipinnate higher up. Pinnre 

 alternate or opposite, generally the former, on the 

 rachis. The basal pinnules of the two lowest pinna? 

 are much longer on the lower than on the upper sides 

 of their midstems or secondary rachides, and these 

 elongated pinnules are again divided into alternate, egg- 

 shaped, and deeply-indented lobes, thus becoming tri- 

 pinnate. The remaining pinnules are less and less 

 divided both towards the apex of the frond and towards 

 the apices of their respective pinnae. Fructification 

 abundant upon the fronds, and consisting of round sori, 

 covered, when young, by the bladder-like or hood-like 

 indusia which are characteristic of the genus Cystopteris. 



HABITATS. Rocky fissures in mountainous districts 

 and the rocky margins of mountain streams. Where 

 rich leaf-mould has collected in such fissures, this species 

 grows luxuriantly, always preferring the most complete 

 shade. 



WHERE FOUND. In Scotland, only in the counties ot 

 Aberdeen, Forfar, and Perth ; the particular districts in 

 the two last-named counties being in Canlochen, at the 



