Adiantum aleuticum - maidenhair fern

Family: Adiantacea
Wetland Indictor Status: FAC

General Species Description

A delicate palmately branched fern with few to solitary leaves branching from stout scaly rhizomes. A small to medium sized fern, 20 to 60 cm tall. They colonize in suitable habitats. The maidenhair fern is easily distinguished by its black stem and horse shoe shape.


The large fan shaped leaves are twice pinnately compound and gro 10 to 40 cm across. Each leaflet is oblong, smooth and flat on the lower margin progressing into ragged rectangular lobes on the upper margin. The edges of the fronds curl over marginal oblong spores sacks that form a protective layer around spores sacks.


Ferns do not reproduce by the use of flowers, instead they reproduce using by using spores formed in little sacs clustered on the underside of the leaves. The spores that land in a suitable moist environment will be able to produce new ferns. Their reproduction depends on availability of moisture at certain seasons.


Ferns do not produce seeds and therefore do not produce fruit.


Maidenhair ferns are found in shady, humus rich sites in moist forests, stream banks, and in spray zones of waterfalls, in low to middle elevations.


Found throughout western Washington and Oregon, extending from lowlands to midmontane, occurrence decreasing with elevation. It occurs in all counties with in the Willamette valley.

Similar Species

There are no other similar ferns found in western Washington.

Ecological Value

Adiantum aleuticum contributes to the overall ecological diversity of Pacific Northwest wetlands.

Human Value

Europeans use an extract from this fern as an ingredient in cough medicine, and it is mixed with sugar to make an emetic.


Cooke, S. S. 1997. A Field Guide to the Common Wetland Plants of Western Washington & Northwestern Oregon. Seattle Audubon Society, Seattle WA, 370 p. Kozloff, Eugene N. 1995. Plants and Animals of the Pacific Northwest. University of Washington Press, Seattle WA, 63 p. Pojar, J. and A. MacKinnon. 1994. Plants of the Pacific Northwest Coast, Washington, Oregon,British Columbia, and Alaska . Lone Star Publishing,Richmond WA 425 p.

This page was created by: S. J. Carey, August 1998

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