Flora of North America species comparison

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Polystichum microchlamys

Polystichum setigerum

attu hollyfern

Alaska holly fern, Alaska sword fern
Stems

erect.

erect.
Leaves

arching, 3–8 dm;

bulblets absent.

arching, 4–10 dm;

bulblets absent.
Petiole

1/8–1/4 length of leaf, densely scaly;

scales brown, diminishing in size distally.

1/8–1/5 length of leaf, densely scaly;

scales light brown, gradually diminishing in size distally.
Blade

broadly lanceolate, 1-pinnate-pinnatifid, base slightly narrowed.

lanceolate, deeply 1-pinnate-pinnatifid to 2-pinnate, base narrowed.
Pinnae

narrowly lanceolate, not overlapping, in 1 plane, 3–13 cm;

base oblique, proximal acroscopic segments enlarged;

margins incised to costa but segments sessile and adnate to costa for at least 2 mm, segments excised and decurrent, serrulate-spiny with teeth spreading to ascending;

apex acute with subapical and apical teeth same size;

microscales filiform, dense abaxially, sparse adaxially.

lanceolate, not overlapping, in 1 plane, 4–8 cm, base oblique, margins incised to costa on middle pinnae, serrulate-spiny with teeth spreading-ascending, apex acute-apiculate with subapical and apical teeth same size;

microscales filiform, sparse abaxially, confined to costa adaxially.
Indusia

erose-dentate.

erose-ciliate.
Spore(s)

color unknown.

brown.
2n

= 246.

Polystichum microchlamys

Polystichum setigerum
Habitat Terrestrial Forest floor in lowland coastal forests
Elevation 0–100 m (0–300 ft) 0–250 m (0–800 ft)
Distribution
from FNA
AK; Asia in Kamtchatka and Japan
[BONAP county map]
from FNA
AK; BC
[BONAP county map]
Discussion

Polystichum microchlamys is found in the flora only on Attu, at the western tip of the Aleutian Archipelago.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Polystichum setigerum is disjunct on Attu Island at the western tip of the Aleutian Archipelago. It is presumed to be of hybrid origin, the result of a cross between P. munitum and P. braunii (D. H. Wagner 1979). This hybrid has been produced experimentally (A. Sleep and T. Reichstein 1967) and is reported from British Columbia (see discussion under P. braunii).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 2. FNA vol. 2.
Parent taxa Dryopteridaceae > Polystichum Dryopteridaceae > Polystichum
Sibling taxa
P. acrostichoides, P. aleuticum, P. andersonii, P. braunii, P. californicum, P. dudleyi, P. imbricans, P. kruckebergii, P. kwakiutlii, P. lemmonii, P. lonchitis, P. munitum, P. scopulinum, P. setigerum
P. acrostichoides, P. aleuticum, P. andersonii, P. braunii, P. californicum, P. dudleyi, P. imbricans, P. kruckebergii, P. kwakiutlii, P. lemmonii, P. lonchitis, P. microchlamys, P. munitum, P. scopulinum
Synonyms Aspidium microchlamys Nephrodium setigerum, P. braunii subsp. alaskense, P. braunii var. alaskense
Name authority (H. Christ) Matsumura: Index Pl. Jap. 1: 343. (1904) (C. Presl) C. Presl: Tent. Pterid. 83. (1836)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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