482 



BOTANY OF THE LIVING PLANT 



present purpose it will suffice to select a few examples, of which the 

 most important will be some common Fern from the large series of 

 the Filicales, and Selaginella from among the Lycopodiales. 



Filicales. 



The living Ferns include more than 7000 species, widely spread over 

 the earth's surface from the Equator to the Arctic Regions. Some 



Fig. 373. 

 Dryopteris Filix-mas, Rich. Fertile leaf about one-sixth natural size, the lower 

 part with the under surface exposed. To the left a single fertile segment, bearing 

 kidney-shaped son, enlarged about seven times. (After Luerssen.) 



39 of these are British. Though a few live actually in water, others 

 are distinctly xerophytic, and able to resist extremes of drought. 



