CHAPTER VII 



EPIPHYTES, PARASITES AND SAPROPHYTES 



EPIPHYTAL PLANTS. A feature especially 

 characteristic of tropical forest floras is that 

 many plants, such as orchids, members of the 

 pine - apple family, some rhododendrons and 

 ferns, make the surface of trees, whether dead 

 or alive, their permanent home. It is chiefly 

 those plants which have very light seeds or 

 spores which get blown up even to the tops 

 of lofty trees. 



Curious adaptations occur in these epiphytic 

 plants to secure a permanent foothold and to 

 supply themselves with water and food. In 

 the orchids aerial roots, having lost the normal 

 tendency of roots to grow down into the soil, 

 clasp the tree-bough in any direction best suit- 

 able, the epidermal cells growing out and 

 gluing the surface of the root by a sort of 

 gummy secretion. Then these roots absorb 

 water with great avidity. These orchids have 

 become adapted to a small amount of light, and 

 as many grow on the tops of high trees, where 

 they are subjected to periodical scorching 



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