142 HISTORY OF BRITISH FERNS. 



will grow freely, provided tliey are not mucli exposed ' to 

 the sun, which they do not like. 



Asplenium fontanum, B. Brown. 



The Smooth Bock Spleenwort. (Plate XII I. fig. 2.) 



This is a small tufted-growing species, seldom seen 

 more than three or four inches high under ordinary cir- 

 cumstances ; in a hothouse, where its parts become more 

 lengthened, it sometimes reaches eight or ten inches high, 

 but this stature is but rarely attained. The small fronds 

 are evergreen, and mostly grow nearly upright ; they are 

 of a narrow, lanceolate form, rather rigid in texture, of a 

 deep green above, paler beneath, and supported on a very 

 short stipes, which has a few narrow pointed scales at the 

 base. They are bipinnate, the pinnae oblong-ovate, and 

 the pinnules obovate, tapering to the base, the superior 

 basal pinnule of each pinna having the margin divided by 

 four or five deep sharp teeth, the rest of the pinnules and 

 lobes having from one to three similar teeth. The main 

 rachis of the frond, as well as the partial rachis of each 

 pinna, has a narrow winged margin ; that is to say, a very 

 narrow leafy expansion along their sides, throughout their 

 length ; and this is, perhaps, the most obvious technical 



