Polystichum aleuticum C. Chr.
Family: Dryopteridaceae
Aleutian shield fern
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Stems erect. Leaves monomorphic, erect, 1--1.5 dm; bulblets absent. Petiole 1/6--1/4 length of leaf; scales tan, sparse or falling off early. Blade linear-lanceolate, 1-pinnate, gradually tapered to base. Pinnae ± deltate to ovate, slightly overlapping, in 1 plane, 4--8 mm; base truncate, acroscopic auricle well developed; margins denticulate, not spiny; apex rounded, not dentate; microscales linear, lacking projections, dense on both surfaces. Indusia entire to minutely erose-dentate. Spores brown. Growing in crevices of rocks; of conservation concern; 0--400 m; Alaska. Polystichum aleuticum is known only from Atka and Adak islands, Alaska. Its nearest relatives are in southwest China. Polystichum aleuticum resembles the dwarfed plants of P . kruckebergii , but it differs, especially, in its smaller, more rounded pinna apices and more abundant scales.

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This project made possible by National Science Foundation Award 1410069