March 1908.] 



203 



Saps and Exudations. 



Manihot dichotoma has this advautage 

 over the other two species, that its seeds 

 germinate very easily, whilst its caout- 

 chouc fetches a somewhat higher price, 

 the seeds being therefore also somewhat 

 more valuable. On the other hand the 

 productivity of the two species from Rio 

 Sao Francisco is de iidedly greater and 

 the method of planting hitherto adopted 

 is much less prejudicial to the trees. 



Whether Manihot heptaphylla or M. 

 piauhyensis is to be preferred for culti- 

 vation cannot yet be asserted with any 

 confidence. On the average the caout- 

 chouc from Manihot piauhyensis is some- 

 what superior to that of Manihot hepta- 

 phylla, and the tree is sooner ripe for 

 tapping; on the other hand the latter 

 seems to be longer lived. 



In Bahia itself no discrimination is yet 

 made, and as a rule that species of 

 Manihot is cultivated which grows wild 

 in the neighbourhood. The culture of 

 M piauhyensis, however, is most widely 

 spread, and continues to extend itself 

 further and further from the Rio Sao 

 Francisco. Manihot piauhyensin would 

 appear to be the most eligible species for 

 cultivation, so long as no special circum- 

 stances intervene. 



In recent years the planting . of Hevea 

 brasiliensis has spread to an unexpected 

 extent, so that millions of these trees 

 have already been planted, which will 

 yield a very notable amount of rubber 

 in the immediate future. No doubt the 

 caoutchouc of Hevea is of higher quality 

 and greater elasticity and always fetches 

 a higher price than that of the Manihot 

 species. Still the cultivation of these 

 species o f Manihot presents certain advan- 

 tages, so that these rubber plants will 

 soon rival Hevea in spite of the greater 

 value o] the caoutchouc produced from 

 the latter.* 



Hevea brasiliensis cannot be tapped 

 before sixyears old, and does uotgive any 

 crop worth speaKing of until eight or ten 

 years, whereas the Manihot species give 

 a good yield in the fourth year. The 

 amount of rubber obtainable per hectare 

 is quite as large from Manihot hepta- 

 phylla and Manihot piauhyensis as from 

 Hevea. The working up of the land 

 required for planting rubber is a much 

 simpler matter in the case of Manihot, 

 since it requires much less labour and 

 trouble to clear and cultivate an area of 

 steppe than to prepare a block of jungle 

 land form Hevea and keep it clean from 

 the vigorously growing undergrowth and 

 lianes. Besides, the most fertile land must 

 be chosen for Hevea, which is not neces- 

 sary in the case of the Manihot species. 



* Ceara rubber is proving to be of higher 

 value.— Ed. 



If, as is probable, the cultivation of 

 Hevea brasiliensis will undoubtedly 

 attain the greatest importance for the 

 production of rubber in luxuriant tro- 

 pical regions, the future lias to look' to 

 Manihot heptaphylla and Manihot piau- 

 hyensis as the rubber plants for the dry 

 and less fertile areas —Tropenpflanzer, 

 Dec. 1907, p. 86. 



[Everyone interested in rubber, and 

 especially in Ceara rubber, should read 

 this paper. The yields are astonishing, 

 and if they should prove reliable, a great 

 difference will be made to the dry north 

 country of Ceylon, where Ceara rubber- 

 does well. So far we have only got seed 

 of one new Manihot, but there is a 

 plantation of this at the Peradeniya 

 Experiment Station, and we expect 

 others.— Ed.] 



ANOTHER NEW INDIA-RUBBER 

 TREE. 



{Bleekrodea Tonkinensis.) 



According to reports in the news- 

 papers a new india-rubber tree has been 

 discovered in Tonkin. Hitherto the 

 only rubber-producing plants known 

 from Indo-China, and especially Tonkin, 

 were Lianes belonging to the family 

 Apocynaceae. The stems of these plants 

 never arrive at any great thickness, and 

 difficulties lie in the way of obtaining 

 rubber from them. The attempt was 

 therefore made to introduce rubber trees 

 such as Hevea brasiliensis, Manihot 

 glaziovii and Ficus elastica into Tonkin, 

 but the result was not satisfactory. 

 Under these circumstances, the discovery 

 of a large india-rubber tree has consider- 

 able importance for the Colony. As 

 Messrs. Dubard and Eberhardt briefly 

 pointed out to the Paris Academy, this 

 tree forms thick Bestande over the whole 

 province of Bac-Kan and in the south of 

 the provinces Bao-Lac and Cao-Bang. 

 It reaches a height of 10-15 metres and 

 grows preferably in Abhangen where the 

 subsoil consists of Kalkschiefer and 

 where there is moist humus, but without 

 stagnant water. Latex obtained from 

 the stem contains a very large amount 

 of Caoutchouc, probably more than that 

 from Hevea brasiliensis. The product is 

 of excellent quality and not to be distin- 

 guished im Handel from the best kinds 

 of Para. The tree belongs to the genus 

 Bleekrodea, Family Moraceae. Only 

 two species of the genus were previously 

 known, one from Madagascar and one 

 from Borneo. The new species has 

 been given the name Bleekrodea Ton- 

 kinensis. 



