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ウェルウィッチア

  • 個体全体
  • 葉の基部
  • 2枚の翼を持った種子
  • 種子
  1. Family name: Welwitschiaceae
  2. Japanese name: UERUITCHIA (KISOTENGAI)
  3. English name: welwitschia
  4. Scientific name: Welwitschia mirabilis
  5. Country of origin: Namibia, Angola (Namib Desert)



Description
It is a special evergreen gymnosperm plant existing as a single species in a single genus in the family. Some are known to live 3,000 years. Only 2 opposite leaves are attached, and the leaves continue to grow for the rest of the year, breaking along the veins as they grow. Leaves grow at the base and wither from the leaf apex. The big leaves can reach a width of 1.8 m and length of 6.2 m. The stalk does not branch, is corklike or woody, and forms a stump shape. Dioecious. It is pollinated by wind and insects. It takes about 25 years to bloom and bear fruit. Propagation is performed by seeding. It is heat tolerant and has high xerotolerance, such as inhabiting regions with annual precipitation of 25–50 mm. It is thought that it absorbs groundwater with the main roots reaching a depth of 3 m or more and absorbs moisture in the atmosphere from the leaf pores. It performs CAM-type photosynthesis.

References
Jacobson, K.M. and Lester, E. 2003. A first assessment of genetic variation in Welwitschia mirabilis Hook. Journal of Heredity. 94: 212-217.
von Willert, D. J., Armbrüster, N., Drees, T. and Zaborowski, M. 2005. Welwitschia mirabilis: CAM or not CAM – what is the answer? Functional Plat Biology. 32: 389-395.
Whitaker, C., Berjak, P., Kolberg, H. and Pammenter, N.W. 2004. Responses to various manipulations, and storage potential, of seeds of the unique desert gymnosperm, Welwitschia mirabilis Hook. fil. South African Journal of Botany 70: 622-630.
Mannheimer, C., Koiberg, H. 1997.カナリア諸島:絶滅危惧種の救済に先駆的な島.p.173-177.朝日百科 植物の世界11巻:種子植物:単子葉類3、裸子植物.朝日新聞社、東京.

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