CHAPTER IX 



THE PARA RUBBER TREE 

 HEVEA BRASILIENSIS, MULL. ARG. 



Species of Hevea. — The trees belonging to the genus 

 Hevea are natives of South America, and up to the present 

 time about twenty species have been described. Tlie 

 most important rubber-yielding species is Hevea hrasili- 

 ensis, Miill. Arg., the well-known Para rubber tree, which 

 is widely distributed in the Amazon valley and furnishes 

 the best rubber of commerce. In addition to this tree, 

 however, a number of the other species of Hevea also 

 yield marketable rubber, and a short notice of these may 

 be given before dealmg in detail with the Para tree. 



Dr. J. Huber, the Director of the Museu Goeldi at 

 Para, has made a special study of the Heveas, and he 

 divides the Brazilian species into three groups according 

 to the quality of the rubber which they fiu-nish. The 

 first group, yielding rubber of the highest quality, is 

 composed of H. hrasiliensis, MiiU. Arg., H. Benthamiana, 

 Miill. Arg., and the closely related species, H. Duckei, 

 Hub. H. hrasiliensis is confined to the southern basin 

 of the Amazon, whereas the other two species are found 

 to the north of the main stream, H. Betithamiana being 

 common on the Rio Negro and H. Duckei on the Yapura 

 river. The smoked rubber of the two latter species is 

 stated to be nearly equal to that of H. hrasiliensis. 



The second group of Hevea consists of H. guianensis, 

 Aubl., H. collina. Hub., H. nigra, Ule, H. cuneata, Hub., 

 H. lutea, Miill. Arg., and H. paludosa, Ule. All these 

 species are stated to yield a second-quality rubber which 

 is smoked in the same way as that of H. hrasiliensis, and 

 is known in Brazil as " borracha fraca " or weak rubber. 

 These trees do not usually grow in the same districts as 

 H. hrasiliensis, and consequently their latices are not 



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