32 
FKRNP. 
[Cystopteris. 
} CYSTOPTERIS FRA GI LIS. 
BRITTLE BLADDER-FERN. 
(Plate II, fig. 2.) 
Cha. — Leaf twice-pinnate, lanceolate. Pinnae ovate- or oblong- 
lanceolate. Pinnules ovate or ovate-lanceolate, deeply cut or toothed. 
a. Pinnules ovate, acute, pinnatifid ; segments toothed ; sori becoming confluent. 
Syn. — Cystea fragilis, E. FI. — Cystopteris fragilis, Hook., in Br. FI., Mack., 
Bernh. — Aspidium fragile, Swz., Hook, in FI. Sco., Willd., Grev., Light/. 
— Polypodium fragile, With., Linn., Linds., Bolt., Hoffrn., Ehrh., Dick. — 
Cyathea fragilis, Roth., Smith in E. B., 8fc., Galp. — Cyclopteris fragilis, 
Sc hr ad., Graij. 
Fig. — E. B. 1587. — Bolt. 45-40. — Flo. Dan. 401. 
Des. — Rootstock black, fibrous, and tufted. Leaves numerous, 
deciduous, bright green, from 6 to 12 inches high, twice pinnate, 
lanceolate, pointed, and finely tapering towards the apex. Rachis 
very brittle and shining, of a dark brown or black colour on the 
lower part, and quite smooth, except a tuft of scales at the very 
base. Pinnse opposite, pointed, about twenty pairs, confined to the 
upper half of the rachis, and growing nearly at right angles to it. 
Their length more than twice their width, except the lower pair, 
which are also distant from the next above them. Pinnules 
alternate, acute, deeply lobed, crenate or bluntly acute, decurrent 
and tapering more or less at the base. Sori numerous, confluent, 
black when young, afterwards a shining brown, and found through- 
out the summer. Indusium white, with an irregular margin, and 
soon obliterated or thrown off by the growing thecae. 
No Ferns are more altered by circumstances than this genus, hence the difficulty 
of distinguishing the species. The varieties, however, are not distinct in them- 
selves, as they may all sometimes he found upon the same plant, and different 
seasons produce differently-shaped and more finely-divided leaves. For example, 
those which arise in ordinary seasons alone answer the above description ; a cold 
spring occasions barren leaves, the pinnules of which are rounded, delicate, wide, 
crenate, and running much into each other, while long-continued drought or warm 
weather occasions those leaves which arise in summer to be much smaller, much 
yellower, more entire, and the sori more crowded. In the extreme state it may 
be described as follows : — Leaf linear, oblong. Pinnae blunt, pinnate, ovate or 
round, toothed, quite covered with sori. If the summer continue very wet and 
cold, the leaves do not take the above character, but have broader and darker- 
coloured pinnules ; in this case exactly resembling the cultivated Cystopteris 
dentata, except in the shape of the leaf itself. 
Sit. — On alpine rocks and other lofty situations. 
Hab. — Eng.: Near Richmond, Yorks., Mr. J. Ward. About Settle, Yorks., 
Mr. J. Tatham. Cumberland, Ruins of Pevcril Castle, Castleton, and the Lover’s 
Leap, near Buxton, Derbys., Mr. II. C. H 'atson. Matlock, Derbys., Dr. Howitt. 
