BRITISH FERNS. 65 



founded on these characters, cannot, with propriety, be retained 

 even as a variety, because, should it hereafter be proved that we 

 possess two or more species of Athyrium in this country, we 

 shall inevitably find the above characters applying occasionally 

 to a frond or plant of every species, and thus we shall have 

 varieties of more than one species named irriguum. 



Filix-femina may be said to possess two distinct types of form, 

 which, although they may occasionally approach, yet, in ninety- 

 nine plants out of every hundred, in a recent state, may be dis- 

 tinguished at a single glance : they may be thus characterised : 



1. Flattened type: the fronds are broad, drooping, heavy, 

 and often of very large size, three, four, and five feet in length : 

 the pinnulae are perfectly flat, and all their cuttings are clearly 

 displayed, and the masses of thecae seldom, perhaps never, become 

 perfectly confluent : the plants of this type vary infinitely in the 

 cutting of the pinnulae, also in the colour of the rachis, which is 

 green, or inclining to red, purple, or even brown ; this form is 

 figured at page 63, and is the Polypodium rhaeticum of Linneus. 



2. Convex type : the fronds are narrower, rigid, erect, light, 

 feathery, and of smaller size, but still occasionally reaching two 

 feet to thirty inches in height : the pinnulae are convex, the 

 margins always being bent downwards, the masses crowded and 

 confluent : the rachis is somewhat pellucid, and very brittle ; it 

 is generally pale green, sometimes nearly white, sometimes of a 

 pink tinge, and sometimes almost as red as coral : this form is 

 figured at page 64, and is the P. Filix-femina of Linneus. 





