Flora of North America species comparison

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Polystichum setigerum

Polystichum andersonii

Alaska holly fern, Alaska sword fern

Anderson's holly-fern, Anderson's sword fern, Vancouver holly fern
Stems

erect.

erect.
Leaves

arching, 4–10 dm;

bulblets absent.

monomorphic, arching, 3–10 dm;

bulblets 1 or more, on distal 1/3 of rachis.
Petiole

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

scales light brown, gradually diminishing in size distally.

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

scales light brown, diminishing in size distally.
Blade

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

lanceolate, 1-pinnate-pinnatifid;

base narrowed.
Pinnae

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.

lanceolate-falcate, proximal pinnae ± triangular, not overlapping, in 1 plane, 2–10 cm;

base oblique, acroscopic auricle well developed;

margins incised to costae, segments adnate to costa for at least 2 mm, serrulate-spiny with teeth ascending;

apex acute with subapical and apical teeth same size;

microscales filiform, with contorted projections, dense abaxially, sparse adaxially.
Indusia

erose-ciliate.

sparsely ciliate.
Spores

brown.

light brown to brown.
2n

= 246.

= 164.

Polystichum setigerum

Polystichum andersonii
Habitat Forest floor in lowland coastal forests Lowland coastal to midmontane forests, interior moist forests
Elevation 0–250 m (0–800 ft) 100–1700 m (300–5600 ft)
Distribution
from FNA
AK; BC
[BONAP county map]
from FNA
AK; ID; MT; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Polystichum andersonii is an allotetraploid (D. H. Wagner 1979); its diploid parents are P. munitum and P. kwakiutlii. The triploid cross, P. munitum × andersonii, has been analyzed cytologically (W. H. Wagner Jr. 1973). It is the only sterile hybrid in the genus that develops large colonies through vegetative propagation by its bulblets. Hybrids look very much like some of the more deeply incised forms of Polystichum munitum except that they have abundant filiform scales, abortive sori, and nearly triangular lowermost pinnae with ± equally incised acroscopic and basiscopic auricles.

(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. microchlamys, P. munitum, P. scopulinum
P. acrostichoides, P. aleuticum, P. braunii, P. californicum, P. dudleyi, P. imbricans, P. kruckebergii, P. kwakiutlii, P. lemmonii, P. lonchitis, P. microchlamys, P. munitum, P. scopulinum, P. setigerum
Synonyms Nephrodium setigerum, P. braunii subsp. alaskense, P. braunii var. alaskense P. braunii subsp. andersonii, P. braunii var. andersonii
Name authority (C. Presl) C. Presl: Tent. Pterid. 83. (1836) M. Hopkins: Amer. Fern J. 3: 116, plate 9. (1913)
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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