34 FERNS IN THEIR HOMES AND OURS. 



although they receive no nourishment from this 

 source. In England, and some parts of this coun- 

 try, the oommon Polypodium has the same habit ; 

 but in the Eastern United States the moisture 

 of the atmosphere is insufficient to enable it to 

 do so. 



Ferns vary in size, from the smallest species 

 of Trichomanes to the huge Tree-Ferns. A 

 fruited plant of Trichomanes Petersii, of Alabama, 

 may be covered, roots and all, with a silver dime ; 

 while the Tree-Ferns sometimes reach the enor- 

 mous height of eighty feet, and bear fronds twen- 

 ty-five feet in length. 



As regards the practical uses of ferns, not much 

 can be said. Their great value is in the share of 

 work they do in Nature's laboratory of air and 

 earth. A few are used in a medicinal way. In 

 some countries the young fronds are cooked and 

 eaten like asparagus, and in Nepaul the natives 

 employ the tubers of a Nephrolepis as an article of 

 food. Adiantum pedatum, the common Maiden- 

 hair, has the honor to serve as a Shaker herb. 

 This matter, however, including the superstitious 

 uses of ferns by people of civilized as well as bar- 

 barous lands, we shall pass by with this simple 

 mention, as it is with their aesthetic value that we 

 have to do. 



The names of ferns (their nomenclature, as it 

 is called) sometimes give considerable trouble to 



