THE PRINCIPAL RUBBER-YIELDING PLANTS 39 



yield of rubber which the trees will furnisli, but experi- 

 ments are in progress in East Africa with the object of 

 determining this point and also the suitability of the 

 trees for cultivation. 



Several other rubber-yielding species of Mascarenhasia 

 occur in Madagascar, viz. M. lisianthi flora, A. DC, 31. 

 aiiceps. Boiv., and .^1/. longijolia, Jum., which collectively 

 fm'nish the rubber known as Gidroa. 



15. Hancornia speciosa, Miill. Arg., the Mangabeira 

 rubber tree. 



This tree is widely distributed throughout Brazil, but 

 the rubber is chiefly collected in the States of Bahia and 

 Pernambuco, and also in Minas Geraes, Goyaz, and Sao 

 Paulo. It is a small tree which bears an edible fruit 

 about the size of a plum. The latex is usually coagulated 

 by the addition of a solution of alum or common salt, and 

 the rubber is frequently impure and of inferior quality. 



16. The African rubber vines belongmg to the natural 

 order Apocynaceae. 



The Apocynaceous rubber vmes occiuTuig in Africa 

 belong almost entirely to the three genera Landolphia, 

 Clitandra, and Carpodmus. These plants are usually 

 found in the forests, where they occur as strong climbers 

 or vmes often of large size ; they attach themselves to 

 the trees on which they grow by means of strong hooked 

 tendrils. A number of the species are also met with on 

 open comitry, where, in the absence of any trees to serve 

 as supports, they develop a bushy habit. In other cases 

 the plants only occiu' as dwarf shrubs or undershrubs 

 with partly herbaceous branches, and the rubber is 

 obtained from their underground stems (rhizomes). 



Rubber vines are widely distributed throughout Central 

 Africa. Their northern limit runs from Senegambia to 

 Abyssinia and their southern limit from Portuguese West 

 Africa to Zululand. Within this area they are found 

 right across the continent and a number of species also 

 occiu' in Madagascar. 



It may, perhaps, be mentioned that there are in Africa 

 many Apocynaceous vines containing latex, which, how- 

 ever, does not yield a marketable rubber. 



The African rubber vines are dealt with in chap, xii, 

 p. 186, but a list of the principal species with their geo- 

 graphical distribution may be given here. 



