MOUNTAIN BLADDER FERN 75 
than these. They may be grown in the open garden- 
border, or in closed cases ; they do best, however, in 
the open air, as they are subject to the attacks of a 
red mildew, which is increased by confinement. 
MOUNTAIN BLADDER FERN. 
CYSTOPTERIS MONTANA, 
Link, Hooker and Arnott, Babington, Moore, and Bentham. 
(Plate X. Fig. 4.) 
SYNONYMS. 
Cystopteris myrrhidifolium, Villars, Pol)podium montanum , Allioni. 
and Newman. Aspidium montanum , Swartz. 
It grows from four ;o eight inches high. The root is 
creeping. The fronds grow simply, and are triangular 
bipinnate; the pinnae of the lowest pair being much 
larger and more divided than the others. The whole 
plant greatly resembles the Oak Polypody, only it is 
of a much more delicate texture. The sori are 
numerous and circular, very conspicuous when fully 
grown, and, though crowded, do not run into masses. 
This rare species of fern occurs wild only in Great 
Britain, although it is found in rough and stony 
places in several parts of the continent of Europe, 
and in America. 
It was first found by Mr. Wilson on Ben Lawers, 
in Forfarshire, in 1836; and has since been established 
by other botanists as a truly British species, though 
rarely to be found. 
