CHAPTER X 



THE CEARA RUBBER TREE, 

 MANIHOT GLAZIOVII, MULL. ARG. 



Species of Manihot. — The Ceara rubber tree and its re- 

 cently discovered allies are natives of north-eastern Brazil 

 and furnish the rubber known as Mani9oba in that country. 

 Until 1901 it was believed that Manihot Glaziovii was the 

 only rubber-yielding species of the genus, but in that 

 year Professor Loigren, the Director of the Botanic 

 Gardens at Sao Paulo, found that Manihot violacea, 

 Miill. Arg., also yields rubber of good quality. This 

 plant, however, is of herbaceous character and has not 

 become of importance as a source of rubber. Subse- 

 quently to this discovery attention was drawn to the 

 Manigoba rubber trees occurring in Bahia by the very 

 large increase in the exports of Mani9oba rubber from 

 that State, which rose from about 24 tons in 1901 to 

 1,444 tons and 1,410 tons in 1905 and 1906 respectively. 

 As the result of the inquiries which were made it was 

 found that the increased production was due to the 

 exploitation of species of Manihot other than M. 

 Glaziovii ; and Professor Ule, who investigated the ques- 

 tion on the spot at the request of the Bahia Rubber 

 Syndicate, was able to establish the existence in north- 

 eastern Brazil of three new rubber-yielding Manihots, 

 which were named M. dichotonvi, Ule, M. heptaphylla, Ule, 

 and M. piauhyensis, Ule. 



In 1906 specimens of seeds, described as those of tiie 

 Jequie Mani9oba {M. dichotoma), were received at Kew, 

 and both seeds and plants raised therefrom were dis- 

 tributed to a number of British Colonies for trial. Sub- 

 sequently seeds of 31. heptaphylla and M. piauhyensis 

 were obtained, and the three new species are at present 



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