Polystichum setigerum

(C. Presl) C. Presl

Tent. Pterid. 83. 1836.

Common names: Alaska sword fern
Basionym: Nephrodium setigerum C. Presl Reliq. Haenk. 1: 37. 1825
Synonyms: P. braunii subsp. alaskense (Maxon) Calder & R. L. Taylor P. braunii var. alaskense (Maxon) Hultén
Treatment appears in FNA Volume 2.

Stems erect. Leaves arching, 4–10 dm; bulblets absent. Petiole 1/8–1/5 length of leaf, densely scaly; scales light brown, gradually diminishing in size distally. Blade lanceolate, deeply 1-pinnate-pinnatifid to 2-pinnate, 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. Indusia erose-ciliate. Spores brown. 2n = 246.

Habitat: Forest floor in lowland coastal forests
Elevation: 0–250 m


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).

Selected References


Lower Taxa