PTERIDOPHYTA. 201 
422. The antherids and archegones resemble those of the 
Horsetails; however, in the highest order (Pepperworts) 
the antherids become greatly reduced. 
423. The ferns are classified mainly upon the structure 
Fic. 112.—A common Fern (Polypodium vulgare) showing the underground 
root-bearing stem, and the leaves, one with round spore-dots on its lower surs 
face, Natural size. 
of their spore-bearing parts. Four orders may thus be 
separated. 
424, The True Ferns (Order Filices) include very nearly 
all the common fern-like plants of our woodlands and hill- 
