





^-23 



Tig. 239. At the left is the " interrupted fern,'' or Clayton's fern (Osmunda 

 Claytoniana), in which sporangimn-bearing leaflets (sp) are distinct and inter- 

 mediate with foliage leaflets. At the right is the royal fern {Osmunda regalis) 



A, a leaf with sporangium-bearing leaflets at its tip. B, C, B, stages in the devel- 

 opment of sporangium-bearing leaflets from foliage leaflets. Both about one 

 third natural size 



287 



