78 



FERNS 



2. Spore-bearing Leaves. In the cinnamon fern the entire 

 leaf is spore-bearing; in the interrupted fern only central 

 pinnee produce spores; in the royal fern only the apical part 

 of the leaf produces spores. In most ferns the spore-bearing 

 tissue is confined to the under side of the leaf. In these cases 



FIG. 42-A 



FIG. 42-B 



FIG. 42-A. Bladder fern (Cystopteris bulbifera) showing two bulbils. 

 FIG. 42-B. Young fern plant developing from the bulbil of Cystopteris 



bulbifera. 



the .spore-bearing tissue has a characteristic arrangement 

 in different species of ferns. The spore-bearing tissues are 

 grouped in special organs called sori (singular, sorns) . Some- 

 times the sori are covered with a thin layer of tissue called 

 the indusium. The spores are in structures called sporangia 



