Royal fern, Osmunda regalis, is a large and conspicuous fern which as a native plant is restricted to damp areas in the western parts of Britain and Ireland, however, it is widely grown in gardens from which it escapes.

Local names include: ash-leaf fern in Cornwall, bog-onion in Cumbria and Ireland, king-fern in Co. Donegal, king-o’-the-ferns in Devon, royal bracken in Scotland, and tree-fern in Wales.

According to a Co. Galway contributor to the Irish Folklore Commission’s 1937-9 Schools Scheme: ‘bog-onion flowers at night in the month of June, but there is some mystery attached to it, because at the approach of daylight the flower disappears.  It is known to be there by leaving seeds after’ [1].

Royal fern was ‘considered a specific for rickets in children’ in Cumberland [2], and, in 1881 it was recorded in the same area, ‘the caudex is still used as an outward application for sprains and bruises: it is beaten and covered with cold water, and allowed to remain thus during the night; in the morning a thick starchy fluid is the result, which is used to bathe the parts affected [3].   Similarly in Co. Clare, bog-onion was pounded and ‘pressed to the sprain and then covered with a bandage [4], and on Colonsay the ‘mucilage from the roots (chopped and steeped in water)’ was applied to sprains [5].

In Co. Galway the root was ‘converted into a juicy substance and used as a rub for rheumatism and sciatica [6].

Royal fern roots were collected  and sold as osmunda fibre for use in orchid cultivation.  R.J. Cooke implies that this was done in Victorian times, when plants were also collected for cultivation in gardens [7].  However, according to Peter Wyse Jackson the ‘plant was formerly collected and harvested [for this purpose] in several parts of the west of Ireland during the late 20th century [8].

Wyse Jackson also records that in 1772 royal fern roots ‘boiled in water is said to be very slimy and to be used in ‘in the North [?of Ireland] for size, to stiffen linen’, similarly, in 1804 in the north of Europe, its roots were used to stiffen linen instead of starch [9].

1. Irish Folklore Commission Schools Scheme, 1937-9, 50: 458.

2. J. Britten & R. Holland, A Dictionary of English Plant-names, [1878-86]: 360.

3. J. Britten, European Ferns, 1881: 178.

4. Irish Folklore Commission Schools Scheme, 1937-9, 593: 43.

5.  W. Milliken & S. Bridgewater, Flora Celtica, 2004: 230.

6. see 1 above.

7. R.J. Cooke, in P.A. Stroh et al., Plant Atlas 2020, 2023: 16.

8.  P. Wyse Jackson, Ireland’s Generous Nature, 2014:  643.

9. Ibid.: 644.

Expanded from Vickery’s Folk Flora, 2019.

Images:  main, cultivated in garth of Chester Cathedral, Cheshire,  September 2024; inset, W.H. Fitch &  W.G. Smith, Illustrations of the British Flora, ed.5, 1949.

25 September 2024