Indicator Plants

Dryopteris expansa – spiny wood fern

Common Name

spiny wood fern



Scientific Name

Dryopteris expansa

Soil Moisture Regime (SMR)
  • Medium (M)
  • Wet (W)
Soil Nutrient Regime (SNR)
  • Medium (M)

Botanical Drawing

Hitchcock, C. Leo, and Arthur Cronquist. Flora of the Pacific Northwest: An Illustrated Manual © 1973. Reprinted with permission of the University of Washington Press.

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

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.


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