著者

服部 靜夫 中原 清士

出版者

公益社団法人 日本植物学会

雑誌

植物学雑誌 (ISSN:0006808X)

巻号頁・発行日

vol.61, no.717-718, pp.37-38, 1948 (Released:2007-06-18)

被引用文献数

2 2

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On the trnnks of pine trees, Pinus densiflora and P. Thunbergii, there are found somewhat globular, large wooden protuberances, the formation of which is caused by the infection of a pathogenous fungus Cronartium quercuum Miyabe. During a relatively short winter period, from the middle of January to the beginning of February in Middle Japan, pale yellow, sweet watery drops are exudated from the cracks of the protuberances. This phenomenon was from an old time known and named“pine honey”by natives. The yellow colour is that of minute spermatia of the fungus, which are formed just at the exudation of sugary liquid. We have been studyiug this curious phenomenon, and found that the sweetness of the exadate is caused by two sugars, namely d-fructose and d-glucose, the amount of the former being 3.3 times that of the latter.The absolute amount of the sugars has been estimated to be about 3.7%, though it would vary according to the duration the liquid experiences after the exudation, that is to say, to the possible evaporation, which in turn varies according to the activity of the plant. That the saccharose, as is the case with sugar maple, does not occur here, together with the fact that the fructose is the leading sugar, is noteworthy.