Polystichum aleuticum C. Christens. Dryopteridaceae Global Distribution: Endemic to Aleutian Islands. Alaska Distribution: Aleutian Meadows. Ecoregions Occupied: Aleutian Islands (Adak Island; a population discovered in 1932 on Atka Island has not been relocated).151 Conservation Status: S1 G1; Endangered. Description25, 152, 153 Leaves up to 15 cm Pinnae margins long toothed, not spiny Indusia entire to irregularly toothed, Stipe bases red- greenish, flat, glabrous brown Pinnae not divided Illustration by Anne-Lillian Schell, courtesy of University of Alaska Museum 227 Polystichum aleuticum General: Tufted fern from stout, dark brown rhizomes; stipes erect, stipe bases red-brown; scales tan, entire, up to 3 mm long, found on all parts of plant but falling off early (absent or sparse at maturity). 1 th 1 th Leaves: Leaves 10 to 15 cm long, bulblets absent; stipes /6 to /4 length of leaves; blade linear-lanceolate, once pinnate, gradually tapered to base. Pinnae: Pinnae arranged in 15 to 20 pairs per leaf, light to dark green, deltate to ovate, slightly overlapping, 3 to 8 mm long; bases abruptly tapering; margins toothed, not spiny; apexes rounded, lacking teeth. Sori: Sori located on upper section of frond; indusia entire to irregularly toothed, greenish, flat, glabrous; spores brown. © Rob Lipkin Ecology Elevation: Known from 340 m to 540 m. Landform: Cliffs, rock outcrops; often in protected areas such as gullies or grottos.154 Soil Type: Rock; often rooting in fissures, crevices, and thinly soiled ledges; associated with volcanic substrates, when soils are present they are usually acidic. Moisture regime: Usually moist. Slope: Steep. 228 Polystichum aleuticum Aspect: East to northeast, these aspects are generally protected from the prevailing winds during the snow-free season.151 Vegetation type: Dwarf willow – sedge meadows, sedge – forb meadows. Associated species: Anemone narcissiflora, Arnica unalaschcensis, Carex macrochaeta, Salix rotundifolia; moss spp. Longevity: Perennial, long-lived.154 Phenology: Leaves appear soon after snow-melt; spores mature July, possibly sooner, through September; phenology likely varies much between years depending on the snow characteristics of specific sites.154 Population estimate: There are four known occurrences in Alaska, not including the occurrence reported from Atka Island, which has not been relocated since 1932;151 total state population is slightly more than 100 individuals,151 although seemingly independent plants may be connected by rhizomes.154 Reproductive biology: Reproduces asexually from rhizomes in addition to the sexual reproduction cycle typical of ferns (having haploid and diploid phases);154 vegetative propagation by rhizomes may be the primary form of reproduction.154 Similar Species25, 152, 153 Polystichum aleuticum is most closely related to Polystichum lachanense, the nearest location of which is in northern Japan. The relationship between these two species is unclear and requires genetic study. They may belong within one species.155 In the Aleutian Islands, Polystichum lonchitis and Cystopteris fragilis can be mistaken for Polystichum aleuticum, especially when they are immature. Woodsia alpina also looks superficially similar but is not known to occur in the Aleutian Islands. The table below distinguishes Polystichum aleuticum from superficially similar species that occur in Alaska. Pinnae Species Leaves Stipes Pinnae Margins Polystichum Up to 15 cm Not jointed at Toothed, not Not divided aleuticum long base spiny Polystichum Up to 60 cm Not jointed at Not divided Spiny lonchitis long base Cystopteris Up to 40 cm Not jointed at Pinnate or Toothed, not fragilis long base pinnatifid spiny Largest pinnae with Entire or Up to 20 cm Woodsia alpina Jointed at base 1 to 3 pairs round- long of major toothed divisions 229 Polystichum aleuticum © Rob Lipkin © Rob Lipkin 230 .