Polystichum aleuticum

Polystichum aleuticum, the Aleutian holly fern[1] 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.[2]

Polystichum aleuticum

Critically Imperiled  (NatureServe)
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Class: Polypodiopsida
Order: Polypodiales
Suborder: Polypodiineae
Family: Dryopteridaceae
Genus: Polystichum
Species:
P. aleuticum
Binomial name
Polystichum aleuticum
C. Christens.

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.[3] It was listed as endangered in 1988.[4] 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.[5][6]

Distribution

It is unlike any other known shield fern found in North America, and originally it was questioned whether it even belonged to the genus Polystichum. However, it was found to be similar to a dwarf Polystichum species native to southwestern mountains of China and the Himalayas.[7]

Description

The Polystichum aleuticum fern is described as erect and approximately six inches tall. It usually found growing alone, rather than in groups. It has a fibrous root with dead leaf remnants attached. Its leaves, visible during the growing season, are light or dark olive green, and tapering.[8] Each of its fronds has 15 to 25 pairs of leaflets (pinnae) that are either sessile or have short stalks and are 4 to 8 mm in length. The upper leaflets each have one spore-producing sori (sometimes two) on the leaflet under surface that is protected by the indusium, a flap of tissue. The spores are produced in July and August.[7]

Notes
  1. "Polystichum aleuticum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 12 October 2015.
  2. "NPWRC :: Endangered and Threatened Species Recovery Program". www.npwrc.usgs.gov. Archived from the original on 2013-07-21. Retrieved 2009-11-18.
  3. "Abstracts: Aleutian shield fern. Prairie fringed orchids". www.faqs.org. Retrieved 2009-11-18.
  4. "Species Profile for Aleutian Shield fern (Polystichum aleuticum)". ecos.fws.gov. Retrieved 2009-11-18.
  5. Sandra Talbot, Steven Talbot. "JSTOR: American Fern Journal, Vol. 92, No. 4 (Oct. - Dec., 2002), pp. 288-293". 92: 288–293. JSTOR 1547136. Cite journal requires |journal= (help)
  6. G. Vernon Byrd, Jeffrey C. Williams (March 2007). "Management Plan for the Alaskan Shield Fern (Polystichum aleuticum) on Adak Island, Alaska" (PDF). PDF. Alaska Maritime National Wildlife Refuge. Retrieved 2009-11-18.
  7. Rumsey, Fred (June 2001). Endangered Wildlife and Plants of the World, Volume 4. PDF. Marshall Cavendish Corporation. p. 258. ISBN 9780761471981. Retrieved 20 November 2009.
  8. "Species Fern, Aleutian Shield". fwie.fw.vt.edu. Archived from the original on 2009-11-24. Retrieved 2009-11-18.
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