Spiny Wood Fern, Spreading woodfern
Dryopteris expansa
Family: Dryopteridaceae
What it is like
Dryopteris expansa is a FERN growing to 0.4 m (1ft 4in) by 0.5 m (1ft 8in). See above for USDA hardiness. It is hardy to UK zone 3. The seeds ripen from July to September. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid and neutral soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers moist soil.
Height (m): 0.4
Where it is found
Cool moist woods, often on rotting logs and tree stumps.
Northern Temperate Zone, including Britain.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 2
Root - raw or cooked. Baked and then peeled before being eaten. The raw root is rather bitter but they develop a sweet taste when cooked and are said by some people to develop a flavour 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-coloured 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.
Root: includes bulbs, corms, tubers, rhizomes etc.
Medicine
Rating: 3
A poultice of the pounded roots has been applied to cuts. We have no other reports for this species, but the following uses apply to many members of this genus and quite probably also to this species. The root contains ‘filicin’, a substance that paralyses tapeworms and other internal parasites and has been used as a worm expellent. It is one of the most effective treatments known for tapeworms - its use should be immediately followed by a non-oily purgative such as magnesium sulphate in order to expel the worms from the body. An oily purge, such as caster oil, increases the absorption of the fern root and can be dangerous. The root is harvested in the autumn and can be dried for later use, it should not be stored for longer than 12 months. This remedy should be used with caution and only under the supervision of a qualified practitioner. The root is toxic and the dosage is critical. See also the notes above on toxicity. The root is also used in the treatment of dandruff.
Anthelmintic: Expels parasites from the gut.
Poultice: A moist, usually warm or hot, mass of plant material applied to the skin in the treatment of burns etc.
Other
Rating: 1
An infusion of the leaves has been used as a hair wash.
Hair: Plants used as hair shampoos, tonics, to treat balding etc.
How it is grown
An easily grown plant, it prefers an acid to neutral soil, succeeding in ordinary fertile soil in a shady position. Prefers a moist soil. Closely related to D. dilatata and hybridising where their ranges meet to produce D. x ambroseae. Members of this genus are rarely if ever troubled by browsing deer.
Propagating it: Spores - can be sown at any time of the year in a greenhouse. Surface sow on a sterilised compost and keep moist, possibly by placing the pot in a plastic bag. Germinates in 1 - 3 months at 20°c. 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.
Best place to grow: Woodland Garden Dappled Shade; Shady Edge; not Deep Shade;
Habit: Fern
Hardiness: 3-7
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Full shade, semi-shade
Moisture: Moist
Things to keep in mind
Although we have found no reports for this species, a number of ferns contain carcinogens so some caution is advisable. The fresh plant contains thiaminase, an enzyme that robs the body of its vitamin B complex. In small quantities this enzyme will do no harm to people eating an adequate diet that is rich in vitamin B, though large quantities can cause severe health problems. The enzyme is destroyed by heat or thorough drying, so cooking the plant will remove the thiaminase. However, there have been reports for other species of ferns suggesting that even cooked fronds can have a long term harmful effect. Some caution is therefore advised.