CYSTOPTERIS. 



71 



GENUS XI, 



CYSTOPTERIS. Bernhardi. 



An interesting, dwarf, elegant, small tribe, with membranaceo- 

 herbaceous fronds. 



The sori medial and covered by an indusium, which is 

 attached by its broad base. 



The veins are simple, forked, or pinnate, from a central 

 costa; the venules being free. 



Fronds much divided. 



Rhizoma tufted, decumbent, or creeping. 



This small genus is a native of the temperate or cold 

 climates, the fronds dying down in winter. 



England boasts of possessing nearly the whole of the species, 

 namely: — Cystopteris fragilis, angustifolia, /^var. of fragilis^) 

 regia, montana, DicMeana, and dentata, (var. oi fragilis. J 



The name is derived from the Greek, and signifies a 

 Bladder Fern, in allusion to the inflated indusia. 



The fronds vary from three to eighteen inches in length. 



Mr. Moore, in "The Genera and Species of Cultivated Ferns," 

 enumerates — 



Fragilis. Bernhardi. 

 Dentata. Hooker. 

 Dickieana. Sim. 

 Bulbifera. Bernhardi. 



Alpina. Desvaux. 

 Tenuis. Schott. 

 Montana. Link. 



Also, in his **Index Filicum,' 



Fragilis. Bernhardi. 

 Regia. Desvaux. 

 Bulbifera. Bernhardi. 



Douglasii. Hooker. 

 Tenuis. Desvaux. 

 Montana. Bernhardi. 



Mr, Moore considers alpina and regia as forms of the same 

 Fern, and fragilis, angustata, dentata, and Dickieana, as all 

 forms of fragilis. 



