KEY TO THE GENERA OF FERNS 



I. Fertile and sterile fronds similar. Sporangia on 



■J'lIE UNDER SIDE OF THE FRONDS, VARIOUSLY CLUS- 

 TERED IN DOTS, LINES, OR ALONC. THE MARGIN. 



With indusium. 



f Sporangia i/nnviim/, or near the margin. Indusium 

 formed of the rcjlcxed margin of the lobes or pinnules, 

 and opening inwardly. 



Fruit-dots oblong, at the end of the veins, on the lobes 

 formed by the cleft upper margiti of the pinnule. Fronds 

 wide crescent-shaped, delicate. Stipe and rachis dark, wiry 

 and shining. Adiauinni^ p. So. 



Sporangia in a continuous, slender line on the man^hi. 

 Fronds large, triangular in outline, ternate. Stipe brownish, 

 heavy. Ptcris, p. 72. 



Fiiiit-dots on the upper side of the veins, distinct at tii-st, 

 but becoming confluent form an apparently continuous tiiar- 

 ghial line. Fertile fronds with narrower divisions than tlie 

 sterile. Stipe and rachis in one species dark and glossy. 

 Fronds smooth, rock-loving. Pclhea^ p. 75. 



ff Fruit-dots ohloiii^ ox linear. Indusium attached by 

 one side, in single or double rows. \\'hen the rows are 

 double the indusia open face to face. 



Fniit-dots on one side or rarely on both sides of oblique 

 vein lets. Fronds variously divided. Several species are 

 small, evergreen, and rock -loving. Aspleiiium, p. 92. 



