December in the hills with Chris Horne and Barbara Mitcalfe
Pneumatopteris pennigera, pākau, gully fern
It is wise to learn the botanical name of this fern, or its Māori name, rather than its common name, so as to avoid confusing its name with gully tree fern, Cyathea cunninghamii. Pneumatopteris means ‘breathing fern’; ‘pteris’ is the Greek word for fern and 'pennigera' means feathery. Some members of the genus have breathing pores at the base of the segments (pinnae).
Distribution and habitat
Pākau is common in damp, shaded, lowland to montane forests on The Three Kings, North, South and Rekohu/Chatham islands. In the southern South Island it occurs mainly in coastal areas. It is absent from Rakiura/Stewart Island. It also occurs in Australia, thus it is native to New Zealand, but not endemic.
Pākau is often a striking feature in damp, shaded, gullies. Although regarded as a ground fern, it often develops a slender trunk up to about 1 metre tall. This is why some people mistake it for a young tree fern. The stipes (stalks) of pākau’s fronds are 5-25 cm long, pale brown and scaly at the base. The fronds are 30-150 cm long x 10-40 cm wide, with dark green, thin segments (pinnae) which occur in 15-30 pairs, the longest 6-20 cm long x 1.5-3 cm wide, the shortest 1-6 cm long. The segments (pinnae), which taper to points, are sessile, i.e., they attach directly to the rachis, so they do not have stalks. The rachis is dark brown and grooved.
Rounded sori develop in two lines, one on each side of the midrib of each segment (pinna). When the sori are ripe, they open, and the spores are distributed by the wind to locations where they may develop into fernlets and later mature adults. See our description of the fern life-cycle in the December 2015 Tramper, on page 11.
Rongoā: The scraped roots have been used as poultices to ‘draw’ boils.
Some Wellington sites
Pākau is abundant along parts of Karori Sanctuary’s Fault-line Track, south of its junction with the Turbine Track. It also occurs in Otari-Wilton’s Bush, in native forest areas in Wellington’s Botanic Garden, and other native bush areas in the city. You may find that it makes an attractive subject for a photograph, on its own, or among other plants in a shaded gully.