SMOOTH BOCK SPLEENWORT. 33 



SMOOTH ROCK SPLEENWORT. 



ASPLENIUM FONTANUM. 



[Bernhardi, Smith, Hooker and Arnott, cmd R. Broum.] 



(Fig. 17.) 



SYNONYMS. 



ASPIDIUM FONTANUM. Swartz. 



ATHYRITJM FONTANUM. Presl and Babington. 



POLYPODIUM FONTANUM. LinnCBUS. 



THIS is one of our rarest British ferns ; indeed, some 

 botanists regard it as an alien. It is a small tufted- 

 growing species, seldom seen more than three or four 

 inches in height. The small fronds are evergreen, and 

 mostly grow upright ; the upper surface is deep green, 

 the under part of a lighter shade. It greatly resembles 

 Asplenium lanceolatum, but is distinguished by its 

 winged rachis. The sori are two to four on each seg- 

 ment, oblong and distinct when young, but when old 

 united into an irregular mass, covering the upper part 

 of the segment. 



This fern may be considered a rarity in England, 



but is sometimes met with on old walls and rocks. It 



was described by Hudson as growing near Wybourn, 



in Westmoreland. It formerly grew on the walls of 



D 



