208 



PTERIDOPHYTA. 



tissue; similar strands are also found in other parts of the 



stem. 



The LEAVES in nearly all species are only foliage-leaves, borne 



FIG. 207. Various Ferns (1, 2, 3, 4). 



in a spiral. They have an apical growth which continues for a 

 long time, and some require several years for their complete de- 

 velopment. In the buds they are rolled up (circinate) ; not only 

 the midrib, but also all the lateral veins, and even the terminal 



