アダック島
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.