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Phegopteris connectilis (Michx.) Watt, Beech Fern

Account Summary

Native, very rare. Circumpolar boreo-temperate.

1860; Smith, Rev Prof R.W.; Brookeborough Deerpark.

June to August.

Growth form and preferred habitats

The triangular annual fronds of Beech Fern with their deflexed pair of lower pinnae in a different plane from the rest of the blade are quite unmistakable, but they are rarely enough seen in Fermanagh. This very misleadingly named fern never occurs under beech trees, the English common name simply being a mistranslation of the Greek 'phegos', which means 'oak'. Nevertheless, oak or beech being equally inappropriate names, this perennial fern is a plant of moist, shady cliffs and damp banks, often near streams, in upland ravine woodlands. The creeping rhizome sometimes allows the plant to develop extensive colonies in undisturbed sites (Jermy et al. 1978). Stunted fronds of Beech Fern are also found where water drips through the roots of other plants on cliff ledges, in crevices and among boulders on rocky slopes.

The species frequents a wide range of rock types and soil pH, but while it appears to prefer soil with a reasonable base content (Page 1997), it can also occur under very acidic conditions, eg on the Mourne granites in Co Down (H38). In the latter situation, it must be presumed that there is some slight base enrichment, however undetected it remains. A degree of inaccessibility tends to assist the survival of this fern since P. connectilis is known to be intolerant of grazing (Sinker et al. 1985).

Fermanagh occurrence

This creeping, rhizomatous fern has been recorded in a total of eight Fermanagh tetrads, but only five of them have post-1975 records.

P. connectilis was first reported in Fermanagh in the grounds of Brookeborough Deerpark by Smith in 1860. Meikle and his co-workers refound it there in the 1950s, but it has not been seen since then at this station (Meikle et al. 1975).

The most interesting site in Fermanagh for the Beech Fern was found by the Rev W.B. Steele in 1929 on the S shore of Lower Lough Erne at Carrickreagh. On its first discovery, it was remarkably abundant on a relatively dry, flattish, limestone woodland floor, under mixed oak, birch and hazel. It remained abundant until 1945 when the site was largely destroyed by the clear felling of the woods and an extension of the nearby quarrying operation (Carrothers et al. 1946). Praeger visited the Carrickreagh site in 1933 and described it in enthusiastic terms, "The fern grows here on limestone rubble thinly covered with humus and mosses, among Primula, Endymion, Hedera, Lysimachia nemorum, Thymus, and Sesleria, forming dense patches up to 20 feet [6 m] across with fronds up to 2 feet [60 cm] high." (Praeger 1934a). In his book The botanist in Ireland, he commented on the Beech Fern at the Carrickreagh site as, "the only habitat of the kind which I know in Ireland, its characteristic stations being wet chinks or ledges in the mountains" (Praeger 1934i). He visited it again around 1938 and reported, "More abundant in the woods of Carrickreagh than anywhere else I have seen it in Ireland; one dense patch measured 250 ft [76.2 m] by 50 ft. [15.24 m]." (Praeger 1939). At present, just one tiny patch survives in this area, consisting of just a couple of fronds on the bank of a stream.

Other current local Fermanagh sites include a strong lowland colony on the Bannagh River near some waterfalls, and the fern also maintains a precarious existence on high ground as tiny fronds in rock crevices on the north face of Cuilcagh mountain.

Irish occurrence

Elsewhere in N Ireland, the species is rare and widely scattered, although locally plentiful in the Mourne Mountains and the wooded Antrim Glens (Hackney et al. 1992). It has many fewer modern stations in N Ireland than was previously the case and a rather similar situation pertains in the Republic of Ireland (An Irish Flora 1996; New Atlas).

British occurrence

P. connectilis is widespread and locally frequent in upland parts of the N and W of Britain, the distribution thinning markedly further south (New Atlas). In these regions, it is most frequent in ancient woodlands dominated by Quercus petraea (Sessile Oak) developed over neutral to acidic soils. In steeper, less accessible gullies in these woods, it frequently occurs on deeper soils percolated with base-rich water (R.J. Cooke, in: Preston et al. 2002).

Throughout the British Isles, P. connectilis tends to follow the distribution of a mountain type of climate, ie cool and with frequent precipitation and high humidity in summer when the fronds are present and growing, and fairly cold in winter when they are not (Page 1997). The summer regime clearly applies throughout the oceanic area of W Ireland including Fermanagh, while the winters in this area are very much milder than in mountainous areas of Great Britain.

The creeping rhizome appears to grow slowly (measurement of just how slowly would make an interesting project), yet the plant is capable of forming very large patches, fully occupying moist, sheltered, generally sloping sites. It therefore appears likely that the plant is long-lived, and thus is an excellent indicator of long-undisturbed sites, perhaps in some instances, with a timescale measured in thousands of years (Page 1997). The evidence gathered for the BSBI New Atlas survey immediately prior to 2000, indicates that the distribution appears stable (Preston et al. 2002).

Reproduction

The nucleus of P. connectilis plant cells contain three sets of chromosomes (ie they are triploid). While the species does manage to produce the gametophyte generation, cell division is unbalanced when meiosis occurs and thus it cannot form normal gametes (ie male and female sex cells). Nevertheless, the fern shortcuts the sexual process and produces new sporophyte plants without fertilisation taking place (ie it reproduces apogamously) (Page 1997).

World occurrence

Beech Fern is widely distributed throughout northern and central temperate parts of Europe and western Asia (Jalas & Suominen 1972, Map 74). Forms of it, including the diploid and tetraploid parents of the British and Irish triploid form, extend it widely around the northern hemisphere making it circumpolar (Hultén 1962, Map 107; Hultén & Fries 1986, Map 39). The taxonomic uncertainties of this group of ferns can be appreciated when one sees that Phegopteris connectilis has belonged in the past to no less than six other genera, including Dryopteris, Thelypteris, Lastrea and Polypodium (Hultén 1962; Hultén & Fries 1986).

Names

The genus name 'Phegopteris' was invented by the Swedish taxonomist, Linnaeus, the Greek 'phelos' referring to a species of oak, not the beech, though the word is cognate with the Latin 'fagus', the name of the Beech tree. The second part of the genus name is also Greek, 'pteris', meaning 'fern' (Gilbert-Carter 1964).

The Latin specific epithet 'connectilis' means 'well connected' (Hyam & Pankhurst 1995). An alternative English common name for the plant is 'Long Beech Fern' (Hyam & Pankhurst 1995) which, like the much more frequent 'Beech Fern', is a 'book name' rather than derived from folk usage (Britten & Holland 1886). The fern does not appear to have had any uses and there is no folklore associated with it.

Threats

The remnant of the Carrickreagh site is threatened by cattle trampling, but the populations at the other Fermanagh sites are kept safe by their remote nature.