CH. II 



CLIMATE 33 



this portion of the zone do not seem to be very different 

 from, although less abundant than, those found in the 

 western part, excepting on higher elevations, where there 

 is a special flora which will be described later under the 

 head of " Influence of Elevation on Forest Growth." 



In tropical America this zone is characterised by the 

 exuberance of growth which called forth the admiration 

 and wonder of early explorers. According to Schimper, 1 

 who has visited both these forests and those of the Indo- 

 Malayan region, the essential features of both are similar, 

 but the trees grow to larger dimensions in tropical 

 America, the liane- stems are thicker, and there is a 

 greater abundance of epiphytes. From many of these 

 depend an immense number of aerial roots " descending 

 vertically and unbranched through the air, forming 

 lightly stretched cords, connecting the climbing and 

 epiphytic Araceae and Clusiaceae with the nutritive soil." 



Among the more notable of the species in these 

 forests in Brazil, Spix and Martius 2 give us the follow- 

 ing : The large silk cotton tree (Bombax pentandrum), 

 relatives of which are found in the African and Indo- 

 Malayan forests ; Lecythis Ollaria, parviflora, Anda 

 braziliensis, Bignonia chrysantha, Spondias Myro- 

 bola,7ius, Sapindus Saponaria, Cedrela odorata, the 

 " Chilian fir " (Araucaria imbricata), etc. ; while among 

 the shrubs are some Myrtaceae, many Rubiaceae, etc. 

 The above description shows a great similarity in the 

 way of genera to the forests of the Indo-Malayan region, 

 only Dipterocarps are absent. 



In more northern forests than those described by 

 Martius we find the Mahogany tree (Swietenia spp.), 

 which in Guiana and British Honduras and the West 

 Indies is a most important article of commerce, as well 

 as Greenheart (Nectandra Rodioei), which is the best 

 wood for resisting attacks of the teredo ; Logwood 

 (HaematoxyJon campechianum) is also an important 

 article of export from British Honduras. 



1 Op. cit., ch. iv. 

 2 Travels in Brazil, by Dr. J. B. von Spix and Dr. C. F. P. von Martius. 



D 



