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Dryopteris expansa

Spiny Wood Fern

At a Glance: A semi-evergreen fern of woodland areas with triangular fronds from a stout rhizome.

Height: To 3 feet (1 meter) tall.
Growth Form: Fern.
Leaves: 3 times pinnate; leaflets 5-20 pairs, the lowest pair broadly triangular and asymmetrical. Tapering toward tip, bottom half of stem bare; shape: blades broadly triangular; size: 20-50 cm (1 m) long; color: green.
Flowering Period: none.
Fruits: Sori rounded, partially covered by the round indusium. Indusium horseshoe-shaped.


Photo © 2005, Starflower Foundation

Sun/Shade Tolerance	Hydrology	Elevation Range
full sun > 80% mostly sunny 60%-80% partial sun and shade 40%- 60% mostly shady 60%-80% full shade > 80%	wet moist dry Wetland Indicator Status: FACW (facultative wetland)	low elevation mid elevation sub-alpine high elevation

Soil Preferences
sandy soils gravelly soils clay soils muddy soils peaty soils	well drained soils shallow soils deep soils acidic soils basic soils	humic soils nutrient rich soils nutrient poor soils mineral soils organic soils

Habitat Preferences
Aquatic and Wetland: Ponds or lakes Shallow pools Sloughs Swales or wet ditches Seasonally inundated areas Marshes or swamps Aquatic bed wetlands Emergent wetlands Scrub-shrub wetlands Forested wetlands Bogs, fens Seeps, springs Shorelines and Riparian: Lake shores Bog margins Streams or rivers Stream or river banks Riparian corridors River bars Floodplains Bottomlands Alluvial areas	Saltwater Areas: In or near saltwater Mud flats Tidal areas Estuaries Saltmarshes Brackish water Seashores Coastal dunes or beaches Rocky or Gravelly Areas: Coastal bluffs Cliffs Rocky slopes Outcrops Crevices Glacial outwash Gullies Slide areas Sub-alpine and Alpine: Heaths Snow beds Tundra Avalanche tracks	Forests and Thickets: Forests and woods Open forests Coniferous forests Old growth forests Deciduous forests Mixed forests Nurse logs Forest edges, openings, or clearings Thickets Meadows and Fields: Pastures or fields Meadows or grassy areas Mossy areas Disturbed Areas: Roadsides Trailsides Logged sites Burned areas Disturbed sites

Wildlife Value

(data not available)

Ethnobotanical Uses and Other Facts

Food Uses: The pineapple-like rootstocks of some forms of spiny wood fern were an important starchy food.
Landscape Uses: Takes to westside gardens well, thriving in partial shade. Does well from spores; well dug small plants establish well.
Ecological Importance: Commonly growing on logs.

Suggested References

Cooke, S.S. A Field Guide to the Common Wetland Plants of Western Washington and Northwetern Oregon. Seattle Audubon Society and Washington Native Plant Society. Page 374.
Hickman, J.C., ed. 1993. The Jepson Manual: Higher Plants of California. University of California Press. Page 92.
Hitchcock, C.L., A. Cronquist. 1973. Vascular Plants of the Pacific Northwest. University of Washington Press. Page 50.
Kruckeberg, A.R. 1996. 2nd ed. Gardening with Native Plants of the Pacific Northwest. University of Washington Press. Page 136.
Pojar, J., A. Mackinnon. 1994. Plants of the Pacific Northwest Coast. Lone Pine Publishing. Page 422.

The landscaping and restoration information provided on this page is taken from Starflower Foundation Image Herbarium. All photographs © Starflower Foundation unless otherwise noted.