Gahnia procera
Common names
giant sedge, gahnia, mountain gahnia
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Sedges
Detailed description
Robust tussock forming perennial sedge. Tufts arising from a short rootstock. Culms 0.3–1.2 m, 2–4 mm diameter. Leaves numerous, ≥ culms, densely crowded at base of culm; lamina up to 1.2 m long, dark green above somewhat paler and often glaucous beneath, narrowly linear, glabrous above, margins flat or recurved otherwise strongly involute when dry, smooth at base, scabrid towards apex; sheaths dull brown, up to 180 mm long. Panicle immersed within foliage, 200–600 × 25–50 mm, more or less drooping, branchlets often in more or less distant clusters. Spikelets 1–(2)-flowered, 9–14 mm long, on slender peduncles or more or less sessile. Glumes 4–5, purple-black, the 2–3 outer glumes empty, lanceolate with a long scabrid awn, the inner 1–2 shorter, deeply concave. Stamens 4–6. Style-branches 4–(5). Nut 5.0–6.5 × 2.0–2.5 mm, brownish orange, or rarely cream, smooth and glossy, ovoid to elliptic-ovoid, occasionally slightly grooved, apex darker, obtuse, rarely scaberulous, wider than the short persistent style-base; endocarp distinctly transversely grooved within.
Similar taxa
Of all the Gahnia species G. procera is most likely to be confused with Gahnia pauciflora which has a similar stature and can grow in similar habitats. From that species G. procera is distinguished by the inflorescences which are usually hidden amongst the foliage rather than towering over it, and by the purple-black glumes with lower sterile glumes > the upper fertile glumes. The nut of G. procera is ovoid to elliptic-ovoid, uniformly coloured brownish-orange (rarely cream) with the tip only slightly darker, while those of G. pauciflora are fusiform, brownish-orange or yellow-cream, with the tip consistently pigmented black. Morelotia affinis (Brong.) Blake although superficially similar is a much smaller plant of lower altitudes whose glumes are spirally rather than distichously arranged.
Distribution
Endemic. North Island, South Island and Stewart Island/Rakiura. In the North Island known from the Coromandel Peninsula south of which it is mostly confined to the main axial ranges. In the South Island confined to the wetter western areas of Nelson, Westland and Fiordland with rare extensions east into Marlborough and Canterbury. Found throughout Stewart Island/Rakiura.
Habitat
Montane to subalpine (up to 1300 m a.s.l.). Usually in forest and subalpine scrub. Mostly in cool, shaded sites on peat but at higher elevations and in cloud forest it often grows in more open sites, in boulder field, on rubble slopes, on cliff faces and on the margins of mires and bogs in subalpine scrub.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Not Threatened
Detailed taxonomy
Family
Synonyms
None
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December–February
Fruiting
Fruit may be found throughout the year
Life cycle and dispersal
Florets are wind dispersed (Thorsen et al., 2009).
Propagation technique
Difficult to culivate. Best results are achieved with seed sown into untreated saw dust. Plants resent root disturbance and usually die if transplanted. 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 partial shade in a damp, humus-enriched but well drained soil.
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). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs in uplands (non-wetlands).
Other information
Etymology
gahnia: After Gahn
procera: Long (filaments)
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.
GAHPRO
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
Otago: 2024 | At Risk – Regionally Naturally Uncommon | Qualifiers: DPS, DPT, NS, Sp
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Regional conservation status of indigenous vascular plants in Otago” Jarvie S et al. (2024) report.
Referencing and citations
References and further reading
Gardner RO. 1996. Gahnia pauciflora and G. procera and a note on G. lacera. Auckland Botanical Society Journal 51: 7–10.
Moore LB, Edgar E. 1970. Flora of New Zealand, Volume II. Indigenous Tracheophyta: Monocotyledones except Gramineae. Government Printer, Wellington, NZ. 354 p.
Thorsen MJ, Dickinson KJM, Seddon PJ. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285–309.
Attribution
Fact Sheet prepared by P.J. de Lange (30 October 2005). Description adapted from Moore and Edgar (1970)
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Gahnia procera Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/gahnia-procera/ (Date website was queried)