Gahnia setifolia
Common name
māpere, gahnia, giant gahnia, razor sedge
Synonyms
Lampocarya setifolia A.Rich.
Family
Cyperaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Sedges
NVS 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.
GAHSET
Current conservation status
The threat classification status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – a suggested threat classification status has not been assessed by the NZTCS panel.
Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Not Threatened
Previous conservation statuses
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Distribution
Endemic. North Island (throughout), South Island (Nelson and Marlborough Sounds)
Habitat
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.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland).
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs in uplands (non-wetlands).
Features
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
Flowering
November - March
Fruiting
Fruits may be found throughout the year
Life cycle
Florets are wind dispersed (Thorsen et al., 2009).
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.
Etymology
gahnia: After Gahn
setifolia: With bristly leaves
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.
Attribution
Fact Sheet prepared by P.J. de Lange (30 October 2005). Description adapted from Moore and Edgar (1970)
References and further reading
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
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Gahnia setifolia Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/gahnia-setifolia/ (Date website was queried)