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Polystichum aleuticum, the Aleutian holly fern or Aleutian shield fern, is an endangered species of the ''Polystichum'' genus and currently consisting of a small, vulnerable population endemic found only on Adak Island, Alaska, a remote island of the Aleutian Islands chain in the northern Pacific Ocean. In 1992, 112 specimens existed in the wild, and a recovery plan was implemented.〔 (【引用サイトリンク】title=NPWRC :: Endangered and Threatened Species Recovery Program ) 〕 The Aleutian shield fern is the only native plant of Alaska on the federal endangered species list. As there are fewer than 150 plants known to exist, it is a very rare North American plant.〔 〕 It was listed as endangered in 1988.〔 〕 ''Polystichum aleuticum'' was first described in 1938, but it could not be located again until 1975 when a group was identified on Mount Reed on Adak Island. A second, third, and fourth population, all on Mount Reed, was located in 1988, 1993, and 1999, respectively. Searches on other Aleutian Islands since 1988 have failed to identify additional populations.〔 〕 ==Distribution== It is unlike any other known shield fern found in North America, and originally it was questioned whether it even belonged to the ''Polystichum'' genus. However, it was found to be similar to a dwarf ''Polystichum'' species located in the southwestern mountains of Asia. 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「Polystichum aleuticum」の詳細全文を読む スポンサード リンク
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