In The Hills In The Hills 2016-10

Asplenium polyodon < Species index > Blechnum colensoi

This article was first published in the Tararua Tramper Volume 88, no 9, October 2016

October in the hills with Chris Horne and Barbara Mitcalfe

Blechnum chambersii, nini, lance fern^*

This is the seventh member of the Blechnum genus described in The Tramper. It is named in honour of Thomas Carrick Chambers, a former University of Auckland student, who studied the Blechnum genus for fifty years. He became Professor of Botany at Melbourne University, and later, Director of the Royal Botanic Gardens, Sydney.

Nini: upright fertile fronds above sterile fronds Photo: JEREMY ROLFE

Habitats

Nini is native to New Zealand, Australia and elsewhere in the Pacific. This wide-ranging fern often grows in dense, extensive colonies, which makes it a visually striking and photogenic feature of many moist, shady, stream-sides and gullies in our region and beyond. Look for this very common fern in lowland to montane forests up to 1.000m elevation throughout New Zealand, except in Otago's drier parts.

Form and reproduction

Nini has stout, erect, rhizomes from which its tufted fronds grow. As you have read in our previous six articles on members of the Blechnum genus, the sterile fronds are distinctly different from the fertile fronds. The dark green, smooth, sterile fronds are narrowly elliptic, 13-50 cm long x 1.5-12 cm wide, They each have 15-40 pairs of segments, the longest in the middle, 0.8-6 cm long x 0.4-1.2 cm wide. They are shorter and more rounded near the base of the frond. Their tips can be blunt or pointed, and their margins are slightly toothed. The bases of the segments are adnate, i.e., they are attached to the frond’s rachis by their whole width.

The fertile fronds, 15-20 cm long x 2-5 cm wide, are a little shorter and narrower than the sterile fronds. Their sori develop in two parallel lines, one on each side of the midrib on the underside of each of the very narrow segments. As the sori ripen and open, the spores they contain are released, then spread by the wind to germinate in a moist, shady site. They then undergo the complete fern life-cycle described in our December 2015 article.

Uses

Māori cooked young fronds of nini, and some other plants, in hangi/earth ovens, to eat as a green vegetable. Because nini is so widespread, it was, and is, easy to find for cooking. Our region has many steep, erosion-prone slopes with dense carpets of nini, which with other plant species, helps to protect the soil from the impacts of heavy rain.

Blechnum chambersii – where to look for it in our region Look for nini beside streams in Otari-Wilton’s Bush; Huntleigh Park; Khandallah Park, Centennial Reserve; the Botanic Garden’s native forest areas; Karori Sanctuary / Zealandia; East Harbour, Belmont and Kaitoke regional parks; Tararua, Rimutaka and Aorangi ranges

See also

Category

Botany 2016

In The Hills 2016-09 < Index chronological > In The Hills 2016-11