THE PRINCIPAL RUBBER-YIELDING PLANTS 35 



The well-prepared rubber, as obtained on the planta- 

 tions in ]Mexico and the West Indies, is of very good 

 quality. 



A further description of this tree is given in chap. xiii. 

 p. 212. 



Another rubber-yielding species of Castilloa, which 

 has been named Castilloa Ulei, Warb., occiu-s in the 

 Upper Amazon valley and furnishes the Caucho rubber 

 obtained from that region. 



7. Ficus spp. A number of rubber-yielding species 

 of Ficus occm' in Asia and Africa, and of these the follow- 

 ing may be mentioned : 



{a) Ficus elastica, Roxb., the Assam rubber tree. 

 This tree, the well-known indiarubber plant grown for 

 ornamental piu-poses in this country, is a native of Assam, 

 Burma, the Malay Peninsula, Sumatra, and Java. In its 

 natural habitat it is a large forest tree with buttress 

 roots, and the branches give rise to numerous adventitious 

 roots which grow to the ground and form subsidiary 

 stems. It has been planted in Assam, the Malay Penin- 

 sula, Sumatra, and Java, but its cultivation has now been 

 largely abandoned in Malaya in favour of the Para tree. 



The rubber of Ficus elasticn is somewhat variable in 

 composition. In some situations the tree furnishes 

 rubber of excellent quality, whereas in others it yields 

 a product containing a considerable percentage of resin. 



A fuller description of this tree will be found in 

 chap. xiv. p. 227. 



(6) Ficus Vogelii, Miq. This tree is a native of West 

 Africa, its habitat extending from the Gambia to the 

 mouth of the Congo. The rubber is of inferior quality 

 on account of the large percentage of resin present, but 

 it is exported from Northern Nigeria under the name of 

 " balata " and is utilised for certain technical purposes 

 (see chap. xiv. p. 234). 



(c) Several African species of Ficus, including Ficus 

 platyphylla, Del., Ficus trachyphylla, Fenzl., and Ficus 

 bibracteata, Warb., yield a hard, resinous product, some- 

 what resembling gutta percha in properties, which is 

 exported from Northern Nigeria (see chap. xiv. p. 236). 



(d) A number of other rubber-yielding species of Ficus 

 are known, such as Ficus Schlechteri, Warb., and Ficus 

 Rigo, Bailey, both of which occur in New Guinea. 



4 



