BRITISH FERNS. 



Polypodium fragile of Linneus and other authors, in its most 

 common form, appears to be the Cystea fragilis of Smith, and is 

 represented in Sowerby's English Botany, pi. 1587, and in 

 Bolton's Filices, pi. 45. As Sir J. E. Smith has taken more 

 pains with this genus than any other of our authors, I shall give 

 his descriptions at length, accompanied in every instance by the 

 figure of a frond, carefully compared with the specimens from 

 which the description is compiled. 



Cystea dentata. Smith. Polypodium dentatum, Dickson. Rather 

 smaller than Cystea fragilis, but agreeing 

 with it in texture, colour, and general aspect. 

 Rhizoma tufted, small. Frond for the most 

 part correctly bipinnate, a few of the lower 

 pinnae only, in luxuriant specimens, being 

 pinnate or pinnatifid ; the pinnulae are ex- 

 actly ovate, or rounded, obtuse, pointless, 

 copiously and bluntly serrated or toothed : 

 their ribs wavy; their base not decurved, 

 ,M though seated on a winged midrib ; masses 

 prominent, at length entirely confluent, of a 

 uniform rich chestnut brown. I do not per- 

 ceive in the younger ones that peculiar black- 

 ness which is observable in P. fragilis. The 

 cover is short, jagged, and concave. I have 

 never seen it in an early stage before burst- 

 ing. Eng. Flora, iv. 300. 



Sir J. E. Smith has described this species, 

 as far as regards the leading characters of the 

 fronds, with great accuracy ; but he has made 

 his species too lax by introducing into it a 

 variety of specimens from Llangollen and 

 Anglesea, which have nothing to do with 

 Dickson's plant. The original plant is solely 

 Scotch, and is the only form of fragilis which 

 I could find on the northern shoulders of 

 Ben More, where it is most abundant, de- 

 scending even to the walls on the road side between Killin and 

 Tyndrum. Sir J. E. Smith appears to have known nothing of 

 the plant but from a dried frond : he makes no allusion to the 

 reflexed, drooping, and convex pinnae of the young fronds, or the 

 more marginal arrangement of the sori, the only characters about 



