Cystopteris. | XCIV. FILICES. | 567 
XIV. CYSTOPTERIS. BLADDERFERN. 
Delicate Ferns, with twice or thrice pinnate fronds. Sori small, circular, 
on the under surface, enclosed, when young, in a very thin, globular, or 
hood-shaped membrane, which opens out irregularly into a cup under one 
side, and often disappears early. 
A small genus limited to the colder or mountainous regions of both 
hemispheres. 
Fronds oblong-lanceolate, the lowest pinnas decreasing in size . 1. C. fragilis. 
Fronds broadly triangular or rhomboidal, the ee ki of peers 
the largest . 3 5 ; : . 2. C. montana, 
id, ©. fragilis, Bernh. (fig. 1305). Brittle Bladderfern.-—Rootstock 
shortly creeping. Fronds tufted, usually under a foot long, oblong-lanceo- 
late in their general outline, twice pinnate; the longest primary pinnas 
towards the middle of the frond, 1 to 13 inches long, decreasing towards 
both ends. Stalks slender, without scales. Segments lanceolate, deeply 
pinnatifid, or the lower ones pinnate, with small, oblong, more or less 
crenate lobes, all obtuse, not pointed as in Asplenium fontanum, to the 
larger specimens of which this plant bears some resemblance. 
On rocks and old walls, spread over the greater part of the globe, 
especially in mountainous districts, extending far into the Arctic regions. 
Dispersed over all Britain, and common in the hilly districts. Fr. summer 
and autumn. A variety from the Alps and Pyrenees, C. alpina, Desv., 
with a 3- 4- pinnate frond, is found in Teesdale. [Another variety is C. 
dentata, Sm., with ovate-lanceolate obtuse segments, and submarginal 
sori. | 
2. C.montana, Bernh. (fig. 1306). Mountain Bladderfern.—Root- 
stock creeping. Fronds growing singly, twice or thrice pinnate, broadly 
triangular or rhomboidal in general outline, the pinnas of the lowest pair 
being considerably larger and more divided than the others, as in Poly- 
podium Dryopteris, which this plant much resembles. It is, however, of 
a more delicate texture, only 6 or 8 inches or rarely a foot high, including 
the long slender stalk ; the pinnas are mostly alternate, with more divided, 
‘smaller segments, and the slender indusium over the sori is easily seen 
under a magnifying-glass when young. 
In moist, alpine situations, in northern and Arctic Europe, Asia and 
America, and i in their great mountain-ranges. In Britain, only on a few 
of the lofty mountains of Scotland. Fr. summer. 
: XV. WOODSIA. WOODSIA. 
Small, tufted, pinnately-divided Ferns, with brown scarious scales or 
hairs on the under surface. Sori circular, surrounded by or intermixed 
with a fringe of chaffy hairs, proceeding from the minute indusium con- 
cealed under the sorus. 
A small genus, still more strictly confined than the last to high northern 
or southern latitudes, or to great elevations. 
1. W. ilvensis, Br, (fig. 1307). Alpine Woodsia.—Stock densely 
tufted. Fronds spreading, 2 to 4 or rarely 6 inches long, twice pinnate, 
