The diseases and pests of the rubber tree . A Twisted Hsvea Stem The photographs on Figs. 31, 32show the stem of a two-year-oldHeoea, two inches in diameter. Ata height of six inches from the groundthe stem makes three complete turns,and above these it is marked by aspiral groove for a length of nineinches. It wiU be seen from thephotographs that this spiral groovebegins near the upper edge of thelast coU. The specimen had beenbroken before it came into my pos-session, and the fracture is shown by the line across themiddle coil, where some of the bark has been broken ofi inthe attempt to fit t
The diseases and pests of the rubber tree . A Twisted Hsvea Stem The photographs on Figs. 31, 32show the stem of a two-year-oldHeoea, two inches in diameter. Ata height of six inches from the groundthe stem makes three complete turns,and above these it is marked by aspiral groove for a length of nineinches. It wiU be seen from thephotographs that this spiral groovebegins near the upper edge of thelast coU. The specimen had beenbroken before it came into my pos-session, and the fracture is shown by the line across themiddle coil, where some of the bark has been broken ofi inthe attempt to fit the two pieces together. The coils arequite free from one another, that is, they are in contact butnot fused together. The stem has undoubtedly been coiledcompletely round three times ; it is not merely grooved. When the stem is broken across the middle turn it is seento be coiled round a much thinner dead stem. This is evidentin the second photograph, which shows the upper part of thestem inverted. From this the explanation of the pheno-. FiQ. 30.—^A ridged stem, x |. 198 THE RUBBER TREE menon is fairly simple. When the young tree was plantedout in the field it was, as usual, stumped. The stem thendied back to the next node, and the new leading shoot sprangfrom the bud at that node. But instead of growing straightup by the side of the dead stem, it coiled round the latterthree times. The cause of this coiling is revealed in the 1 .fBI ( ? ?9^^1 ::..:^i 1 \ f f
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Keywords: ., bookcentury1900, bookdecade1920, bookidcu3192400285, bookyear1921
