Osmunda regalis L., Royal Fern

Account Summary

Growth form and preferred habitats

This large, robust, rhizomatous, clump-forming fern with its tall, broad, erect, bipinnately divided, distinctive light-green sterile fronds up to 3 or even 4 m tall also produces separate, smaller, fertile fronds with rusty spike-like clusters of sporangia. O. regalis is a very conspicuous and unmistakable calcifuge species of fens, bogs, lakeshores, streamsides and ditches. While Royal Fern is typically a species of wet, acid, peat conditions, when necessary it can tolerate the considerable base-enrichment associated with salt-laden coastal winds on sea cliffs and the like (Jermy et al. 1978; Page 1997).

Ecology and longevity

In spite of the large robust nature of the sterile fronds and their leathery appearance, the aerial parts shrivel and die-back at the first serious touch of frost (Step & Jackson 1945). While in nature it is relatively slow growing, Royal Fern is probably one of the longest lived native ferns in Britain & Ireland. Large individuals in garden cultivation are known to be over 100 years old, and their thick, erect, rhizome bases display no signs of decline. Comparisons of massive wild ferns, based on the size of such garden specimens, suggest some individuals must be many centuries old (Page 1997).

Fermanagh occurrence

The tetrad map of its Fermanagh occurrence gives an over-optimistic picture of Osmunda's frequency in the VC. While it appears to be widely distributed in the S & W of the county and scattered elsewhere, at many of the 70 post-1975 tetrads there are only one or two plants recorded. Furthermore, the high frequency of pre-1975 sites where the plant has not recently been seen (20 tetrads on the map), suggests that either there has been a decline of the species in the area, or it was merely casual in its occurrence at these sites.

British and Irish occurrence

It has a mainly, but not exclusively, western and southern distribution in Britain & Ireland, although it is more coastal in Britain and more definitely western in Ireland (Jermy et al. 1978; New Atlas).

From at least the time of the Victorian fern craze in the 1850's, plants of this fern have been collected for garden use, both as a decorative subject in itself, and because the fibres of its large leaf bases provide an ideal horticultural medium for growing orchids (Allen 1969). We have no evidence of this wholesale collecting ever happening in Fermanagh, or if it has, it is at an insignificant frequency compared with some places in England, for instance in Westmorland where the species has been depleted by collecting, almost to extinction (Halliday 1997).

As a result of the widespread garden cultivation of the fern, particularly in Britain, it is not a simple matter to separate native occurrences from naturalised garden escapes or discards, a point which must be borne in mind when studying the detail in distribution maps of the species (Jermy et al. 1978; New Atlas).

O. regalis has undoubtedly declined considerably in N Ireland due to habitat loss associated with drainage and, in the E of the province, from development, for instance in bogs around Donaghadee in Co Down (Hackney et al. 1992). Apart from the Lough Neagh basin, the Fermanagh records probably constitute the most easterly large concentration of sites of the fern in Ireland. However, the species is very much associated with areas of high rainfall, and thus it is decidedly western in its distribution anyway.

European and world occurrence

Royal Fern being very variable and polymorphic, on the world scale it is best examined in the broad sense as an aggregate species. In Europe, O. regalis has its main area of distribution in the W and S of the continent, from the S Swedish coast to the Azores and it ranges discontinuously across the Mediterranean to Crete, Turkey and the Caucasus (Jales & Suominen 1972, Map 50; Page 1997).

On a world basis, Hultén (1958), and again in Hultén & Fries (1986 Map 29), map this polymorphic species along with three varieties they recognise, so that in total it stretches in a decidedly disjunct manner from Europe and C & S Africa to the Cape, a small pocket in N India and the Himalaya, to China, Burma and Japan, to eastern N America and parts of S America.

Names

The genus name 'Osmunda' is derived either from 'Osmund the Waterman' (an English Common name given by Lyte (1578), since it is a fern of bogs and streamsides), or from the Anglo-Saxon equivalent of the name 'Thor', the Scandinavian god of thunder (Grigson 1974; Gledhill 1985). The specific epithet 'regalis', Latin meaning 'kingly' or 'royal', apparently refers to the dignified and impressive appearance of the plant, and its great longevity (Gilbert-Carter 1964).

The plant has a long list of local English Common names, some of which date back to Anglo-Saxon, others of the 16th century. One of the most interesting is 'Herb Christopher' or 'St Christopher's Herb', which appears in Lyte (1578), Gerard (1597) and later authors. These names allude to the waterside habitat of the fern which the saint frequented and where, before he was converted, he exercised his self-imposed task of carrying people across fords. A very odd name is 'Bog Onion', from Cumberland, the explanation of which entirely defeats the current writer (Britten & Holland 1886; Vickery 1985).

Uses

The root or rhizome of O. regalis has been used not only as a potting compost as mentioned above, but also medicinally. The supposed curative powers are attributed to the salts of lime and potash, amongst others, which it obtains from the bog soil and water in which the fern grows. It was prescribed by herbalists for treating jaundice in its early stages, or for removing alimentary obstructions. An ointment made from the root was also recommended for healing wounds, including bruises, dislocations and lumbago (Grieve 1931).

Threats

Mechanical peat cutting on lowland raised bogs is the main threat, in many of the sites.

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