Polypody 



EXPLANATION OF TERMS 



A FERN is a flowerless plant 

 growing from a rootstock (a), with 

 leaves or fronds usuallj' raised on 

 a stalk, rolled up {b) in the bud,* 

 and bearing on their lower surfaces 

 {c) the spores, by means of which 

 the plant reproduces. 



A rootstock is an underground, 

 rooting stem. Ferns are propa- 

 gated by the growth and budding 

 of the rootstock as well as by the 

 ordinary method of reproduction. 

 The fronds spring from the root- 

 stock in the manner peculiar to 

 the species to which they belong. The 

 Osmundas, the Evergreen Wood Fern, 

 and others grow in a crown or circle, 

 the younger fronds always inside. 

 The Mountain Spleenwort is one of 

 a class which has irregularly clus- 



* Ophioglossum and the Botrychiums, not beins 

 true ferns, are exceptions. 

 38 



