n EQUATORIAL VEGETATION 243 



whose trunks are formed by a miniature forest of aerial roots, 

 sometimes separate, sometimes matted together, are charac- 

 teristic of the Eastern tropics, but appear to be rare or alto- 

 gether unknown in America, and can therefore hardly be 

 included among the general characteristics of the equatorial 

 zone. 



Besides the varieties of form, however, the tree-trunks of 

 these forests present many peculiarities of colour and texture. 

 The majority are rather smooth -barked, and many are of 

 peculiar whitish, green, yellowish, or brown colours, or occa- 

 sionally nearly black. Some are perfectly smooth, others 

 deeply cracked and furrowed, while in a considerable number 

 the bark splits off in flakes or hangs down in long fibrous 

 ribands. Spined or prickly trunks (except of palms) are rare 

 in the damp equatorial forests. Turning our gaze upwards 

 from the stems to the foliage, we find two types of leaf not 

 common in the temperate zone, although the great mass of 

 the trees offer nothing very remarkable in this respect. 

 First, we have many trees with large, thick, and glossy leaves, 

 like those of the cherry -laurel or the magnolia, but even 

 larger, smoother, and more symmetrical. The leaves of the 

 Asiatic caoutchouc tree (Ficus elastica), so often cultivated in 

 houses, is a type of this class, which has a very fine effect 

 among the more ordinary-looking foliage. Contrasted with 

 this is the fine pinnate foliage of some of the largest forest 

 trees, which, seen far aloft against the sky, looks as delicate as 

 that of the sensitive mimosa. 



Forest Trees of Low Growth 



The great trees we have hitherto been describing form, 

 however, but a portion of the forest. Beneath their lofty 

 canopy there often exists a second forest of moderate-sized 

 trees, whose crowns, perhaps forty or fifty feet high, do not 

 touch the lowermost branches of those above them. These 

 are of course shade-loving trees, and their presence effectually 

 prevents the growth of any young trees of the larger kinds, 

 until, overcome by age and storms, some monarch of the 

 forest falls down, and, carrying destruction in its fall, opens 

 up a considerable space into which sun and air can penetrate. 

 Then comes a race for existence among the seedlings of the 



