56. 



"but the lichens "begin to appear, With the further 

 rise of evaporstion, the mosses also disappear leartring 

 only the lichens to occupy the areas of highest evapo- 

 ration. 



The definite distribution of epiphytes on the 

 tree corresponds somewhat to the results obtained by 

 Shreve (26) in the Blue mountains of Jamaica. He says 

 p,!5y#**^e trees of the upper slopes have the same 

 epiphytic flora that v/ould be found in the upper 

 two-thirds of the trees of the ravines, The trees of 

 the ridges and peaks have only those that are 

 characteristic of the uppermost third and the midheight 

 species are restricted in these habitats to the side 

 of prostrate trunks or fallen logsJThus, the vertical 

 and radial distribution of epiphytes on an individual 

 tree appears to be comparable to a certain degree t o 

 the similar distribution of epiphytes in the mountains J 

 Not only idthe vertical distribution of the epiphytes 

 on an individual tree well marked but even at the same 

 height different sides of the tree will bear different 

 types of epiphytes, as is shown in the ease of Q. stellata 

 where, for instance, at ten meters above ground the south 

 side of the trunk bears only mosses, while the northeast 

 and the northwest sides bear huge clumps of the poiypody 

 entangled in mosses, It was found, however, that at 

 different sides at the same height and at different heights 

 of the same tree the evaporating power of the air i a 



