Dryopteris expansa – spiny wood fern
Common Name
spiny wood fern
Family
Dryopteridaceae
Scientific Name
Dryopteris expansa
Soil Moisture Regime (SMR)
- Medium (M)
- Wet (W)
Soil Nutrient Regime (SNR)
- Medium (M)
Video link
Hitchcock, C. Leo, and Arthur Cronquist. Flora of the Pacific Northwest: An Illustrated Manual © 1973. Reprinted with permission of the University of Washington Press.
Photo Gallery
General / Habitat
- Clustered, erect fern
- Grows in moist forests and openings
- Low to subalpine elevations
Key Identifying Characteristics
- Form: up to 1 m tall,
- Leaves:
- Stipes (stalk below the blade) scaly at the base
- Blades (leafy part of the frond) broadly triangular
- Triply-pinnate (tripinnate) (leaflets have subleaflets have subleaflets)
- Lowest pair of leaflets assymetrical with inner, downward pointing pair of leaflets much longer than others, like spurs
- Flowers: Rounded sori, partially covered by rounded indusium
Lookalikes
- Athyrium filix-femina (lady fern)
- Lowest leaflets relatively small
- Pteridinium aquilinum (bracken)
- More triangular, flatter, lower pair of leaflets very large
External References
Sources
Douglas, G.W. et al (Editors). 1998-2002. Illustrated Flora of British Columbia, Volumes 1 to 8. B.C. Min. Environ., Lands and Parks, and B.C. Min. For., Victoria, B.C.
Pojar, J. and A. MacKinnon. 2014. Plants of Coastal British Columbia Including Washington, Oregon & Alaska. B.C. Ministry of Forestry and Lone Pine Publishing. Vancouver, B.C.