September in the hills with Chris Horne
Adiantum cunninghamii, huruhuru tapairu, common maidenhair
This endemic fern is one of seven members of the genus Adiantum in our flora. Collectively called maidenhair ferns, they all feature shiny, dark-brown stalks/stipes and stems/rachises.
Origin of the names
Adiantum, from the Greek word ‘adiantos’, meaning ‘unwetted’, refers to the fronds remaining as if dry after being plunged into water; cunninghamii refers to Allan Cunningham (1791-1839), an English botanist, stationed in Australia, who collected plants in New Zealand. The Adiantum ferns have several Māori names, e.g., huruhuru tapairu, makawe tapairu, tawatawa. ‘Huruhuru’ means ‘coarse hair’, ‘bristles’; ‘tapairu’ means ‘honoured lady’ – hence ‘maidenhair’; ‘makawe’ means ‘hair of the head’ or ‘ringlet’. The verb ‘tawatawa’ means ‘to be mottled, like the skin of a mackerel’.
Distribution and habitat
Common maidenhair is our most widespread and abundant species of Adiantum. Look for it in coastal and lowland forest, bush remnants, on cliffs, banks, limestone areas and among boulders, up to about 500 m elevation. You can find it on Te Ika a Māui/North Island, Te Wai Pounamu/South Island, the Kermadec, Three Kings, Rakiura/Stewart and Rekohu/Chatham Islands.
The stout, far-creeping rhizome is clad in stiff, dark-brown scales up to 8mm long.
Common maidenhair is a small ground fern. Its fronds are 10-35 cm long x 5-24 cm wide. The segments/pinnae are more or less oblong, tending to curve towards the apex. The upper edges of a segment are irregularly toothed, the lower edge is smooth. The segments are dark green above, and blue-green below. The wiry, shining, almost black stalk/stipe is attached to one corner of a segment.
Indusia are thin, kidney-shaped outgrowths of tissue which cover the spores/sori. As the indusia mature, they shrivel and bend backwards to expose the spore capsules/sporangia. Ripe spores are then spread by the wind to produce young maidenhair ferns.
Māori prepared a lotion from the fronds and roots of common maidenhair. Adiantum fern species remain popular in the UK, a left-over from a fern craze there in the 1800s.
Where to look for common maidenhair
Look for this widespread fern in Otari-Wilton’s Bush, Wellington Botanic Garden, Huntleigh Park, Khandallah Park, Long Gully Bush Reserve, the southern North Island coast, and the Rimutaka, Tararua and Aorangi ranges. Its completely hairless frond, and the oblong segments which are often bluish-green on the underside, will help you to identify it.