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''Rheum nobile'', the Noble rhubarb or Sikkim rhubarb or पदमचाल, is a giant herbaceous plant native to the Himalaya, from northeastern Afghanistan, east through northern Pakistan and India, Nepal, Sikkim (in India), Bhutan, and Tibet to Myanmar, occurring in the alpine zone at 4000–4800 m altitude. It is an extraordinary species of rhubarb (genus ''Rheum''). At 1–2 m tall, ''R. nobile'' towers above all the shrubs and low herbs in its habitat, and it is visible across valleys a mile away. ''R. nobile'' is often called a ''glasshouse plant'' because of its outer curtain of translucent bracts which pass visible light, creating a greenhouse effect, while blocking ultraviolet radiation. These are important defenses against the increased UV-B exposure and extreme cold in its high altitude range.〔Iwashina et al. p.101〕 ==Structure== An individual ''R. nobile'' is a conical tower of delicate, straw-coloured, shining, translucent, regularly overlapping bracts; the higher ones have pink edges. Large, glossy, green radicle leaves, with red petioles and nerves, form a broad base to the plant. Turning up the bracts reveals membranous, fragile, pink stipules. Within these are short branched panicles of diminutive green flowers.〔Hooker p.94〕 The root is often long and as thick as an arm, and bright yellow inside. The stems are pleasantly acidic, and they are consumed by the local people, who call the plant ''Chuka''. The hollow of the stem contains a good deal of limpid water. After flowering, the stem lengthens and the bracts separate one from another, turning a coarse red-brown. As the fruit ripens, the bracts fall away, leaving a ragged-looking stem covered with panicles of deep brown pendulous fruits. As Hooker put their appearance: ''"In the winter, these naked black stems, projecting from the beetling cliffs, or towering above the snow, are in dismal keeping with the surrounding desolation of that season."''.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rheum nobile」の詳細全文を読む スポンサード リンク
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