POLYPODIUM. 145 



roots may be placed within the reach of the water. For 

 the margins of ponds or lakes, or for any other damp loca- 

 lities, it is also well adapted ; and in such situations only 

 does it acquire anything like its natural vigour. It should 

 have peat earth for its roots. The best way to establish 

 it is, to procure strong vigorous patches from localities 

 where it abounds, and these, if removed carefully any time 

 before growth commences or even after it is considerably 

 advanced will succeed perfectly. This course is far more 

 satisfactory than to make use of weaker plants in the hope 

 of their eventually gaining the requisite vigour to produce 

 the effect desired. 



Genus I. POLYPODIUM, Zinnaws. 



THE Polypodies, which botanists call by the Latin name of 

 Polypodium, are known from all the other British Perns, 

 by their having the spore-cases arranged in little round 

 patches here and there on the back of the frond, these 

 patches not being at any time, or at any stage of their 

 development, covered by the membranous film which, it 

 has been explained, is called an indusium ; hence they are 

 said to be naked, or non-indusiate. This family includes 



L 



