274 



MO-RPHOLOGY. 



ferns are examples of this interesting relation between the leaves 

 like the common sensitive fern (( Jnoclea sensibilis) and the 

 ostrich fern (( ). struthiopteris) and the cinnamon fern (Osmunda 

 cinnamomea). The sensitive fern is here shown in fig. 316. 

 The sterile leaves are large, broadly expanded, and pinnate, the 





Fig. 316. 

 Sensitive fern ; normal condition of vegetative leaves and sporophylls. 



pinnas being cjuite large. The fertile lea\es arc shown also in 

 the figure, and at first one would not take them for lca\es at all. 

 ]iut if we examine them carefully «c see that the general plan 

 of the leaf is the same : the two rows of jiinna; which are here 

 much shorter than in the sterile leaf, and the pinnules, or smaller 



