104 HISTORY OF BRITISH FERNS. 



the sori while in a young state, but becoming ultimately 

 reflexed at the point, which is more or less jagged or fringed. 

 Hence these plants are called Bladder Terns. There are 

 three native species, of one of which numerous distinct 

 forms or varieties occur. 



The technical name comes from two Greek words, kystos, 

 and pteris, which respectively mean bladder, and fern ; so 

 that in this case the English appellation is a literal trans- 

 lation of the scientific name. 



CYSTOPTERIS ALPINA, Desvaux. The Alpine Bladder- 

 Fern. (Plate X. fig. 2.) 



A diminutive but very elegant plant, quite a gem. It 

 has a close tufted stem, producing from its crown numerous 

 bright green fronds, usually four to six inches, but some- 

 times as much as ten inches high. These grow up in May, 

 and die away in autumn. Their form is lanceolate, the 

 mode of division bipinnate, with the pinnules so deeply pin- 

 natifid as to render them almost tripinnate. The stipes is 

 short, smooth, and scaly at the base. The pinnse are nearly 

 opposite, with a winged rachis, ovate, divided into bluntly 

 ovate pinnules, these latter being deeply cleft, almost down 

 to their mid vein, into short, blunt, linear lobes, which are 

 either entire, or have two or three blunt teeth. 



