Maidenhair fern  (Adiantum capillus-veneris)

The maidenhair fern has yet to be classified by the IUCN.

A delicate-looking, drooping fern with distinctive fan-shaped leaf segments, the maidenhair fern (Adiantum capillus-veneris) possesses many clustered fronds (large, divided leaves) on wiry black stems (2) (3) (4) (5). It spreads by means of short, creeping rhizomes, covered in small brown scales, which sometimes appear reddish-brown or golden (2) (4) (5) (6) (7) (8). The fronds are arching and hairless, occasionally with a bluish-green or waxy (glaucous) tinge to the normally pale green leaves, which are pinnate, with individual leaflets often lobed or toothed along the margins (3) (4) (6) (7) (8).

The genus name of the maidenhair fern, Adiantum, is derived from the Greek word ‘Adiantos’ - meaning ‘unwetted’ - as the leaves of the fern repel water, while the species name is taken from the Latin words ‘capillus’ and ‘veneris’, meaning ‘hair of Venus’, giving this plant its alternative common name, the Venus maidenhair fern (2) (9).

The maidenhair fern is widespread throughout tropical and temperate regions of the world, and is found in North, South and Central America, Mexico, Canada (British Columbia), Europe, Asia, Africa and Australia (2) (4) (5) (7) (8) (9).

Requiring fairly warm and humid conditions, the maidenhair fern is found in shaded, moist areas where it typically grows on rock faces and in crevices of cliffs, on banks and ledges along streams and rivers, or close to natural hot springs (3) (5) (6) (7) (8) (9).

The maidenhair fern reproduces both vegetatively and from spores. It sporulates (produces and disperses spores) during the spring and summer (7), with the spores of the maidenhair fern produced and contained in structures called sporangia, which are grouped into clusters known as ‘sori’, on the outer edges of the leaflet’s lower surface. The edges of the leaves fold over to form a crescent-shaped protective flap, called an ‘indusium’ (2) (4) (5) (6) (7) (8).   

Although the maidenhair fern is widespread worldwide, in Australia and Canada it is only known from single sites, where it is threatened by habitat loss and degradation due to human development. Additional threats include collection, disturbance and invasive species (4) (8).

Similar problems may threaten other populations of the maidenhair fern around the world; however, as yet no quantitative research has been carried out. 

In Australia, the maidenhair fern is listed as a threatened taxon on Schedule 2 of the Flora and Fauna Guarantee Act 1988 (4), while in Canada it is a red-listed species in British Colombia, where it is considered Endangered (8).

In Canada, the maidenhair fern occurs on privately owned land, and, although it is not currently protected, it is hoped that a single-species recovery strategy will soon be implemented (5). Elsewhere, there are no known conservation measures in place for the maidenhair fern. 

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To find out more about the recovery strategy for the maidenhair fern in Canada, see:

• Recovery strategy for the southern maiden-hair fern (Adiantum capillus-veneris) in British Columbia:
  http://www.env.gov.bc.ca/wld/documents/recovery/rcvrystrat/southern_maidenhairfern_rcvry_strat_281107.pdf

To find out more about plants and fungi, see:

• Royal Botanic Gardens, Kew:
  http://www.kew.org/