KEY TO THE GENERA 



The distinguishing characters of the different genera 

 may be found by referring to the following key, and 

 with the genus known it is usually an easy matter to as- 

 certain the species. It will be observed that the fruiting 

 portion of the ferns is not always on the backs of the 

 ordinary fronds; in some species it is borne on separate 

 stalks. For this reason the ferns are divided into two 

 general classes in the key: 



1st. — Those in which the sporangia are not borne on 

 the backs of the ordinary fronds. 



2nd. — Those in which the sporangia are borne on the 

 backs of the ordinary fronds. 

 Sporangia not borne on the backs of the ordinary fronds. 



B C 



Osmunda. 



Fruiting portion borne in the middle of the frond. 

 Clayton's Fern, A. 



1 



