Dryopteris expansa
northern fern, spreading wood fern
Specimens
Photos

Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to Alberta, Idaho, and Montana.

Habitat: Moist to wet woods and streambanks.

Origin: Native

Conservation Status: Not of concern

Description:
General:

Perennial with stems creeping to erect, dying back in winter delayed, lacking stolons.

Leaves:

Leaves monomorphic, 90 cm long and 30 cm broad; petiole 1/3 length of leaf; scales found at least at base, scattered, brown with dark brown stripe; blade green, deltate-ovate, 3-pinnate-pinnafitid, typically eglandular, sometimes densely fine-glandular; pinnae generally in same plane as blade, lanceolate-pblong, basal pinnae deltate and slightly reduced, basal pinnules longer than or equal to others, basal basiscopic pinnule longer than basal acroscopic pinnule, pinnule margins serrate.

Spores:

Sori halfway between midvein and segment margins; indusia glands absent or slightly glandular, round-reniform, attached at narrow sinus; spores brownish.

Accepted Name:
Dryopteris expansa (C. Presl) Fraser-Jenk. & Jermy
Publication: Brit. Fern Gaz. 11: 338. 1977. 1977.

Synonyms & Misapplications:
Dryopteris assimilis S. Walker
Dryopteris campyloptera (Kunze) Clarkson, misapplied [FNA2]
Dryopteris dilatata (Hoffm.) A. Gray, misapplied [Abrams, Peck]
Dryopteris dilitata (Hoffm.) A. Gray var. americana (Fisch.) Hultén
Nephrodium expansum C. Presl
Additional Resources:

PNW Herbaria: Specimen records of Dryopteris expansa in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Dryopteris expansa checklist entry.

E-Flora BC: Dryopteris expansa atlas page.

CalPhotos: Dryopteris expansa photos.

USDA Plants: Dryopteris expansa information.

15 photographs:
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