Common Name: Interrupted Fern

General Information

Osmunda claytoniana is a
herbaceous fern growing up to 50cm all. Plants are usually deciduous, but can be evergreen in areas with warm winters[].
The plant is harvested from the wild for local use as a food and a medicine. It is a source of a fibre used for making potting mixes for growing orchids, and is sometimes grown as an ornamental.

Known Hazards

Although we have found no reports of toxicity for this species, a number of ferns contain carcinogens so some caution is advisable[].
Many ferns also contain 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[].

Botanical References

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Range

E. Asia - China, Japan, Himalayas. Eastern N. America - southern Ontario to Newfoundland, south to Tennessee and N. Carolina.

Habitat

Wet places in C. Japan[]. Open slopes, rarely in forests; at elevations from 2,800 - 3,300 metres in Kashmir[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Fern
Height	0.50 m
Cultivation Status	Ornamental, Wild

Cultivation Details

Osmunda claytoniana is cold-hardy to at least -20°c. The plants can be evergreen in warm winter areas but deciduous elsewhere[].
Likes a soil of swamp mud and loamy or fibrous peat, sand and loam[]. Succeeds in most moist soils, preferring acid conditions[]. Requires a constant supply of water, doing well by ponds, streams etc[]. Plants thrive in full sun so long as there is no shortage of moisture in the soil and also in shady situations beneath shrubs etc[]. Requires a shady position[].
Members of this genus are rarely if ever troubled by browsing deer[].
A very ornamental plant[].

Edible Uses

The young fronds are eaten[]. Cooked as a vegetable[, ].

The centre of the clump, below ground level, is the source of a small edible pith called 'fern butter'[].

Medicinal

The roots are used as an adulterant for Dryopteris felix-mas in the treatment of internal worms[].

Other Uses

The heavy rhizomes are a source for 'Osmunda fibre', which is used in potting mixtures for growing orchids[].

Propagation

Spores - they very quickly lose their viability (within 3 days) and are best sown as soon as they are ripe on the surface of a humus-rich sterilized soil in a lightly shaded place in a greenhouse. Keep the compost moist, preferably by putting a plastic bag over the pot. Plants develop very rapidly, pot on small clumps of plantlets as soon as they are large enough to handle and keep humid until they are well established. Do not plant outside until the ferns are at least 2 years old. Cultivars usually come true to type[].
Division of the rootstock in the dormant season. This is a very strenuous exercise due to the mass of wiry roots[].