Ill] 



THE BRACKEN FERN 



35 





Fig. 5. Leaf of the male Shield-Fern (Nephrodium filix-mas, Kich.), 

 about one-eighth natural size, the lower part having the under 

 surface exposed. To the left a single segment, bearing the sori, 

 each covered by its kidney-shaped indusium. (After Luerssen.) 



32 



