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Adiantum capillus-veneris L., Maidenhair Fern

Account Summary

Native and naturalised garden introduction, very rare. Mediterranean-Atlantic.

1939; Praeger, R.Ll.; on the walls of Crom Castle.

May to August.

Growth form and preferred habitats

This is a small to moderate sized, delicate-looking, rhizomatous fern with fronds divided into numerous small, fan-shaped segments borne on thin, blackish, wire-like branches. It is frost-tender and a rare or very rare species mainly of damp, mild, limestone coastal areas of W Ireland and SW Britain. In very sheltered sites fronds are sometimes semi-evergreen, surviving overwinter. Native populations are threatened by unthinking collectors.

Apart from its scattered natural sites, Maidenhair Fern is frequently cultivated (mainly indoors), and can sometimes be found 'escaped' on sheltered, damp, lime-rich mortar on garden walls near old greenhouses.

Variation

Plants are rather variable in size, degree of frond dissection and margin serration, so that extreme forms have been brought into cultivation and have become named as horticultural cultivars (Page 1997).

Fermanagh occurrence

Praeger's original Fermanagh station was given as, "On outer side of wall opposite main door of Crom Castle" (Praeger 1939). It continues to thrive on the boat house at Crom, approximately 100 m from the old castle, and it is also abundant on the garden wall of Florencecourt against which a greenhouse once stood. These naturalised plants are the only recognised records of this fern in N Ireland, several 19th century finds in coastal stations in Down (H38) and Co Antrim (H39) having been discarded as either errors or unconfirmed and, in any event, now extinct (Hackney et al. 1992).

European and world occurrence

Maidenhair Fern is essentially a Mediterranean Basin and S Atlantic species, although Hultén (1962, Map 139) maps it as circumpolar in warm-temperate latitudes of the northern hemisphere. It is also widespread around the southern hemisphere, including appearances in some very remote island groups.

Irish occurrence

A. capillus-veneris occurs as a native species in Ireland only in scattered stations along the W coast, most abundantly in the Burren, Co Clare (where it is especially luxuriant and impressive on Inishmore, Aran Islands) (H9) and in SW Donegal (H35) (Jermy et al. 1978; Scannell & Synnott 1987). The latter, since the Antrim stations are discarded, must now be regarded as the most northerly site of the species anywhere in the world (Hultén 1962; Jalas & Suominen 1972). The New Atlas map displays nine Irish hectads scattered across the island where this fern has been recorded as an introduction.

British occurrence

In Britain, A. capillus-veneris is native in scattered sites from the Channel Isles and the SW coast, up the W coast from Cornwall, through S Wales to Cumbria and the Isle of Man (Jermy et al. 1978; Page 1997; New Atlas). This rather delicate-looking fern also crops up in Britain from time to time as established escapes from cultivation at inland sites in lime-rich mortar or on limestone walls, exactly as it does in Fermanagh (Jermy & Camus 1991).

Names

The genus name 'Adiantum' is a Greek plant name used by ancient botanical writers, derived from 'adiantos' meaning 'dry' or 'unwetted', an allusion to the non-wettable character of the foliage, a feature known to Pliny (Step & Jackson 1945; Gilbert-Carter 1964). The Latin specific epithet 'capillus-veneris', means 'Hair of Venus', and hence the English Common name 'Maidenhair Fern'. 'Capillus veneris' was the medieval Latin name used by apothecaries for this medicinal fern, a name first found in the Herbarius of the fourth century AD ascribed to Apuleius, and it refers to wiry pubic hair which are likened to the blackish stalks of the fern fronds (Grigson 1974).

Additional local common names include 'Capillaire', 'Lady's Hair' and 'Dudder-grass', the latter a strange Norfolk usage, apparently making comparison with Briza media (Quaking-grass or Dodder-grass), because of the trembling motion of the frond segments resembling the movement of the grass spikelets (Britten & Holland 1886).

Uses

Medicinal use dates back to Dioscorides, as a remedy in pectoral complaints and pulmonary catarrhs (Grieve 1931).

Threats

The species has died out at a number of previous stations along the coasts of Ireland, England and Wales. Either of the two Fermanagh sites could easily be destroyed by re-plastering of stonework or other excessive or unknowing 'tidying' operations.