n] 



EPIPHYTIC HABIT 



45 



Drynaria by the dififerentiation of the leaves into two types. In the latter 

 genus the nest-leaves are widely expanded, growing appressed to the surface 

 of the trunk or branch, and are sterile. They are pale coloured, and have a 

 strong venation, which persists after the mesophyll decays, forming a basket- 

 like receptacle for humus in which the adventitious roots are nourished. 



Fig. 52. Aspleiiiiim nidus, an epiphytic Nest Fern. E. Borneo. 

 (After M. Muhlberg, from Christ.) 



Other leaves develop of a normal type, and are photo-synthetic and fertile 

 (Fig. 53)- In Platyceriwn the method is the same, though with different 

 details (Fig. 54). The affinities of the two genera are widely. distinct, and 

 their resemblances are clearly homoplastic. The general method of these 

 epiphytes is not unlike that seen in Bromeliads and Orchids. 



