VEGETATION OF THE RAIN-FOREST. 23 



Nearly all the trees on slopes, even many young ones, show a leaning 

 down hill (see plate 12), larger ones are often bent over nearly to the 

 horizontal, while the number of down-fallen trunks, all pointing down 

 hill, indicates only too clearly the destructive influence of erosion on 

 the older trees. Only along the beds of valleys where the soil is rela- 

 tively stable have I seen trees of more than 30 inches (76 cm.) trunk 

 diameter, these usually being Solarium punctulatum or Gilibertia arborea. 



The forests of the Blue Mountains exhibit an intermingling of tem- 

 perate and tropical characteristics both in their composition and their 

 general ecology. I made no exact determinations of the composition 

 of the forest because of the impossibility of securing satisfactory data 

 where the rapidity of erosion causes so many complications in the forest 

 stand. However, rough estimations which I made in a number of 

 localities indicated that Clethra occidentalis, Vaccinium meridionale, and 

 Podocarpus urbanii form about 50 per cent of the stand and that an 

 additional 35 per cent is made up of some 10 other species, as follows : 

 Alchornea latifolia, Cyrilla racemiflora, Ilex montana var. occidentalis, 

 Guarea swartzii, BruneUia comocladifolia, Clusia havetioides, Gilibertia 

 arborea, Rapanea ferruginea, Solarium punctulatum, and Eugenia biflora 

 var. wallennii. In other words, the general character of the composi- 

 tion is that of temperate forests rather than of those in tropical lowland-. 

 The examinations which I have made of virgin lowland forests in the 

 valley of the Mabess River in the northeastern part of Jamaica and in 

 the vicinity of Mount Diablo, in the central part, make me quite 

 confident in stating that they are far more complex in their composition 

 than the mountain forests and more so than the forests of the Philippine 

 Islands which have been described by Whit ford. 1 The constant 

 overturning of the largest trees by erosion gives opportunity for the 

 entrance of young individuals, and results in a great diversity in trunk 

 diameters. Clethra, Vaccinium, and Podocarpus all sucker freely from 

 old roots and trunks, so that a single root system often anchors a thick 

 horizontal trunk and several young vertical ones, which adds still 

 further to this diversity. 



The individual trees are mostly of temperate rather than of tropical 

 type in the order of branching and shape of the crown. In Vaccinium, 

 Podocarpus, Clethra, Ilex, and other common forms the order of branch- 

 ing varies from the seventh to the ninth, or is even higher; in BruneUia 

 comocladifolia alone is there a low order the fourth. In Rapanea 

 ferruginea the lateral branches exceed the main trunk in growth; in 

 BruneUia there is a lax, open crown, and in Eugenia fragrans and 

 Eugenia alpina there are round compact heads of foliage With these 

 exceptions there are no trees which present any peculiarities of form. 

 The bark is universally smooth and thin. Cauliflory 1<<^ not occur. 



1 Whitford, H. N. The Vegetation of the I.amao I'm.'- Reserve. Philip. Jour. S, i . I. 

 373 431. G37-G82. 1906. 



