THE PRINCIPAL RUBBER- YIELDING PLANTS 31 



yielding plants of the world grouped according to their 

 natui"al orders : 



I. EUPHORBIACEAE 



1. Hevea brasiliensis, ]\Iull. Arg., the Para rubber tree. 

 This is the most important rubber-yielding plant, 



since it fm'nishes the greater part of the world's supply of 

 rubber, either from wild trees m the Amazon valley 

 or from cultivated trees in Asia. The rubber derived from 

 this tree is also of the highest quality, and the " fine 

 hard Para " from South America forms the market 

 standard of price. 



Hevea brasiliensis is a large forest tree which occurs 

 wild throughout the entire valley of the Amazon and 

 its tributaries to the south of the main stream. It has 

 been found to grow weU in suitable situations through- 

 out the tropics, and is now being cultivated extensively 

 in Ceylon, the Malay Peninsula, India, Sumatra, Java, 

 and other countries. 



A number of other species of Hevea also occur in South 

 America, some of which are known to yield good rubber, 

 but they are of less importance than Hevea brasiliensis. 



A description of the Pcira rubber tree and its allies is 

 given in chap. ix. p. 101.. 



2. Manihot Glaziovii, MiiU. Arg., the Ceara rubber tree. 

 This tree is a native of the north-eastern portion of 



Brazil, especially in the province of Ceara, where the 

 climate is much drier than in the Amazon valley. It 

 furnishes the rubber known as Manigoba in Brazil. 



The Ceara tree has been introduced into almost aU 

 tropical countries, and it is now being cultivated on a 

 large scale in East Africa. If carefuUy prepared, the 

 rubber is of excellent quality, and plantation Ceara rubber 

 is practically equal in value to plantation Para. 



Three other species of Manihot which also jdeld rub- 

 ber have been discovered within the last few years in 

 eastern Brazil and have been named Manihot dichotoma, 

 M . heptaphylla, and M. piaukyensis. It is stated that 

 in Brazil these species are superior to Manihot Glaziovii 

 as sources of rubber, and they are being cultivated ex- 

 perimentally in many countries at the present time for 

 comparison with the Ceara tree. 



