RUBBER PLANTING 29 



an elevation of 3000 to 5000 feet It is a small tree 

 with narrow leaves <jnd a drooping habit like that of 

 a weeping birch. The fruit is yellow and edible, some- 

 what resembling a plum. Tapping is carried out in 

 various ways similar to those adopted in the case of 

 Manihot, but it is said that all the different processes 

 are leading to the extinction of the plant. Coagulation 

 is generally effected by the addition of a solution of 

 alum or some other salt. The result is a wet rubber 

 which is not much valued in this country. The yield of 

 rubber is, however, said to be considerable, and the 

 plant appears to deserve closer attention than it has 

 hitherto received. 



The same remark applies to some of the species of 

 Sapium, which grow at high elevations in Colombia and 

 Guiana. The Sapiums are large and hardy trees ; 

 nevertheless they have been largely exterminated in 

 their native forests by reckless tapping. 



Other rubber-producing species of the Western 

 Hemisphere deserving of mention are Forsterionia 

 gracilis in Guiana and F. floribunda in Jamaica. These 

 are climbing plants comparable with the Landolphias of 

 Africa. 



Guayule Rubber. 



Before proceeding to describe the wild rubbers of 

 Africa and Asia, mention must be made of one other 

 American species of strikingly different habit from those 

 so far enumerated. This is Parthcnium argentatum, 



