CHAPTER III 



THE PRINCIPAL RUBBER- YIELDING PLANTS 



Geographical Distribution. — The riibber-yieldiiig plants 

 arc practically restricted to the tropics, and theii^ extreme 

 geogiaphical limits may be placed at about 28° north 

 and south of the equator. They are most widely dis- 

 tributed in Central and South America and in tropical 

 Africa, as the portion of Asia lying within the above- 

 mentioned limits is only small. 



In America the area in which rubber plants are in- 

 digenous comprises Mexico, the States of Central America, 

 some of the West Indian islands, Colombia, Venezuela' 

 the Guianas, Ecuador, Peru, Bolivia, and Brazil. 



Rubber plants are also found over practically the 

 whole of Central Africa. They extend from Senegambia 

 through West Africa, across the French Congo into the 

 Bahr-el-Ghazal Province of the Anglo-Egyptian Sudan, 

 and thence into Abyssinia. South of this line they are 

 found right across the continent and also in Madagascar, 

 the southern limit running from Portuguese West 

 Africa through Rhodesia and the northern part of the 

 Transvaal to Zululand on the east coast. 



In Asia the occurrence of wild rubber plants is limited 

 to India, Indo-China, the Malay Peninsula and the 

 neighbouring islands. Rubber plants are also indigenous 

 in New Guinea, Fiji, and other islands of the Pacific. 



Botanical Source.— The principal rubber-yielding plants 

 belong to one of the three natural orders Euphorbiaceae, 

 Urticaceae, and Apocynaceae. A few of lesser importance 

 belong to the natural order Asclepiadaceae, and the 

 Guayule rubber plant of Mexico {Parthenhim argentaium) 

 is noteworthy in belonging to the order Compositae. 



Plants belonging to these natural orders are quite 



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