io8 HOW TO KNOW THE FERNS 



sheathing, are to be found the spore capsules. 

 These cases are of two kinds, those on the 

 outermost rows of leaves containing the large 

 spores, and those on the inner leaves being 

 responsible for the small spores. 



Isoetes lacustris. The Quillwort. 



The Quillwort is often abundant in mountain 

 lakes in Scotland and the North of England. 

 Owing to its habit of growth, however, the 

 plant is usually unnoticed by the majority of 

 people. 



Another species of Quillwort Isoetes Hys- 

 trix occurs in the Channel Islands, but it 



