MESOPHYTE SOCIETIES. 



247 



numerous saprophytes occur. Such an assemblage of vege- 

 tation is to be found nowhere else. 



(3) Number of species. -Not only is there an immense 

 number of individuals, but an extraordinary number of 

 species occur. A list of 



plants growing in these 

 forests would show a re- 

 markable representation of 

 the plant kingdom. 



(4) Forms of trees. 

 The dense vegetation re- 

 sults in 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 inter- 

 ference is so great that 

 the development of low 

 branches is impossible. It 

 is common,, also, .for the 

 larger trees to develop a 

 system of buttresses near 

 the base, and also fre- 

 quently 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 during the period of cold. The same device would be 

 sufficient to protect against a period of drouth. In the 

 tropical forest there is danger neither from cold nor drouth, 

 and in such conditions bud scales are not developed, and 

 the buds remain naked and unprotected. 



(6) Devices against too abundant rain. The abundance 



17 



FIG. 203. A gutter-pointed leaf from a 

 tropical plant. After SCHIMPER. 



