Plant Data Sheet


Spreading Wood Fern

Spreading Wood Fern, Photo courtesy Wisconsin State Herbarium and Sue R. CrispinPhotographer: Sue R. Crispin

Dryopteris expansa



Alaska to Newfoundland and Greenland, south to California, Idaho, Wyoming, Minnesota, Wisconsin, and Michigan. Also found in Central Europe. Ecozones: Boreal Shield and Pacific Maritime.


Climate, elevation

Cool moist woods and rocky slopes. Hardy to an annual minimum average temperature of -40F.


Local occurrence

Rare. Usually found in rocky ground or woods.


Habitat preferences

Woods, hedgebanks, wet heaths, shady rock ledges and crevices. Shade to bright shade. Does well in woodlands or next to a stream or pond. It prefers cool, moist redwood and mixed evergreen forests, often growing on rotting logs, tree stumps and rocky slopes. As a riparian plant, it is associated with stream banks.


Plant strategy type/successional stage (stress-tolerator, competitor, weedy/colonizer, seral, late successional)


Associated species

One of the parents of D. campyloptera





Collection restrictions or guidelines

The raw root is rather bitter but they develop a sweet taste when cooked and are said by some people to develop a flavor rather like sweet potatoes. The root is best harvested in early autumn. At this time the rhizomes are surrounded by scaly, finger-like projections - if the projections are flat and dark inside then the rhizomes are not good to eat but if they are round, fleshy and light-colored then they can be eaten. The young shoots, harvested in spring before they have fully unfurled, can be cooked and eaten. They can be added to soups.


Propagation recommendations (plant seeds, vegetative parts, cuttings, etc.)

Spores - can be sown at any time of the year in a greenhouse. Surface sow on a sterilized compost and keep moist, possibly by placing the pot in a plastic bag. Germinates in 1 - 3 months at 20c. Pot up small clumps of the plants when they are large enough to handle and grow on in a shady part of the greenhouse until large enough to plant out. Division in spring. Larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring.


Soil or medium requirements

It prefers moist, acidic and neutral soil and does well in sand, loam and clay.



Sources cited

  1. Plant List for Willapa NWR Porter Point
  2. The Rook Family Homepage
  3. Rainy Side Gardeners
  4. Skye Flora
  5. Wikipedia
  6. Plants for a Future



Data compiled by Robert Franco 4/13/06