Gahnia setifolia


Gahnia: after Gahn
setifolia: with bristly leaves

Common Name(s)

mapere, Gahnia, giant Gahnia, razor sedge

Current Conservation Status

2012 - Not Threatened

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - Not Threatened
2004 - Not Threatened


Gahnia setifolia (A.Rich.) Hook.f.



Flora Category

Vascular - Native

NVS Species Code


The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

Structural Class



Lampocarya setifolia A.Rich.


Endemic. North Island (throughout), South Island (Nelson and Marlborough Sounds)


Coastal to montane (up to 780 m a.s.l. - possibly higher). Mostly in lowland areas in light forest, scrub along logging tracks in pine plantations and cut over indigenous forest and lining streams, rivers, ponds and lakes. Sometimes colonising the fringes of swamps, bogs and mires.


Robust, large perennial sedge arising from a stout, lignaceous rootstock and forming tufts up to 3 m tall. Culms 10-15 mm diameter (but up to 20 mm at the base). leaves more or less = to culms in length; lamina dark green to yellow green above paler and often glaucous beneath, harshly scabrid, rugose, margins involute and scabrid with a few longitudinal rows of teeth just inside the margin on the upper lamina surface; sheaths up to 300 mm long, dull brownish-black. Panicle robust up to 1 m long, drooping, branches numerous, primary branchlets up to 400 mm long, Spikelets 2-flowered, 6-7 mm long, stalked, dark red-brown to blackish brown. Glumes 6-7; 3-4 outermost empty, 5-6 mm long, 3 inner glumes 4 mm long in young flowers white with a red-brown apex, becoming dark red-brown throughout as fruit matures. Stamens 4(-6). Style-branches 3. Nut 3.5-4.5 mm long, 1.9-2 mm diameter, elliptic-obovoid, smooth and glossy, yellow-cream at first, maturing reddish brown when fully ripe; endocarp transversely grooved within.

Similar Taxa

Gahnia setifolia could only ever be confused with the other giants of the New Zealand species G. rigida Kirk and G. xanthocarpa (Hook.f.) Hook.f. Of these species G. setifolia most frequently grows with G. xanthocarpa which differs by its glossy light to dark green leaves, reddish brown spikelets which are > 7 mm long, and dark glossy black nuts which are > 5 mm long. From G. rigida, G. setifolia differs by its drooping rather than rigidly erect panicle and reddish brown rather than bicoloured light brown/dark brown nuts with black centres


November - March


Fruits may be found throughout the year

Propagation Technique

Can be difficult to cultivate. The seed is difficult to germinate, and plants resent root disturbance and usually die if transplanted. However, considerable success has been achieved growing plants and/or germinating seed in untreated saw dust. Despite these problems this is an attractive species well worth attempting to grow. Once established it flourishes in a range of conditions but does best in full sun in a well drained or only seasonally wet soil.


Not Threatened

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Florets are wind dispersed (Thorsen et al., 2009).

Cultural Use/Importance

Mapere is often known as razor sedge on account of its wickedly sharp leaves which are a constant hazard to those pushing tracks through places where this species has become well established. Mapere flourishes on damp clay and other forest soils, such as those left exposed following logging operations.


Fact Sheet prepared by P.J. de Lange (30 October 2005). Description adapted from Moore and Edgar (1970)

References and further reading

Gardner, R.O. 1995. Identifying Gahnia setifolia and G. xanthocarpa. Auckland Botanical Society Journal, 50: 82-83.

Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.

Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309


This page last updated on 20 Nov 2015