MESOPHYTE ASSOCIATIONS. 



255 



straight leafless tree-trunks, so that the leaves of trees are 

 mainly clustered at the tops of high branches. The shade 

 is so dense and the interference is so great that the devel- 

 opment of low branches is impossible. It is common, also, 



Fig. 213. A group of aerial plants (epiphytes) from a tropical forest. Note the vari- 

 ous habits of the epiphytes attached to the tree-trunks, and the dangling roots.— 

 After Schimper. 



for the larger trees to develop a system of buttresses near 

 the base, and also frequently to send out prop roots (see 

 Figs. 100, 101). 



(5) Absence of bud scales. — In the deciduous forest bud 

 scales are necessary to protect the tender growing tips din> 

 ing the period of cold. The same device would be suffi- 

 18 



