Gahnia xanthocarpa
Common names
gahnia, māpere
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Sedges
Flower colours
Brown, Red/Pink
Detailed description
Robust perennial sedge arising from a lignaceous rootstock up to 30 mm diameter and forming densely tufted dark green tussocks up to 3.5 m tall. Culms 10 mm diameter (but up to 15 mm diameter at the base). Leaves slightly ≤ culms, not usually overtopping the panicle; lamina dark glossy green above, paler beneath, surfaces harshly scabrid, margins involute, ciliate just above the transverse line demarcating the sheath from the lamina, becoming more intensely scabrid higher up with a few longitudinal rows of teeth just inside the margin on the lamina undersides; sheaths dull, light pinkish brown, glabrous up to 40 mm wide. Panicles set well above foliage, drooping, 0.6–1.5 m long, heavily branched, primary branchlets up to 450 mm long. Spikelets 2-flowered, c. 8 mm long, numerous, densely crowded, stalked, light chestnut-brown. Glumes 6–7; outer 3–4 empty, more or less equal, 7–8 mm long; inner 3 glumes smaller, 5–6 mm long, red-brown, or green-brown below and red brown towards apices. Stamens 4, bright red-brown. Style-branches 3–4. Nut 5–6 × 2–3 mm, fusiform, bright yellow maturing glossy black when fully ripe, sometimes slightly grooved, shortly stipitate, with alight orange-brown, obtuse, pubescent apex; endocarp transversely grooved within.
Similar taxa
Gahnia xanthocarpa could only ever be confused with the other giants of the New Zealand species G. setifolia (A. Rich.) Hook.f. and G. rigida Kirk. Gahnia xanthocarpa frequently grows with G. setifolia from which it is easily distinguished by its glossy dark green leaves, reddish brown spikelets which are > 7 mm long and dark glossy black nuts which are > 5 mm long. Gahnia xanthocarpa rarely grows with G. rigida from which it is easily distinguished by its drooping rather than rigidly erect panicle and dark glossy black nuts.
Distribution
Endemic. North Island (from Te Paki south to Wellington but uncommon, or absent over some parts of this range), South Island (Nelson, Marlborough, Westland and Canterbury—where it is very uncommon).
Habitat
Coastal to montane (up to 800 m a.s.l., possibly more). Occupying a diverse range of habitats and vegetation associations, Gahnia xanthocarpa seems to prefer permanently damp situations within alluvial forest, swamp forest and the margins of lowland swamps, bogs and waterways.
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
Genus
Family
Synonyms
Lampocarya xanthocarpa Hook.f.; Gahnia ebenocarpa Hook.f. ex Kirk; Claudium xanthocarpum (Hook.f.) F.Muell.; Gahnia setifolia (A.Rich.) Hook.f. var. xanthocarpa (Hook.f.) Kük.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
January–April
Fruiting
Fruits may be found throughout the year
Life cycle and dispersal
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 planted in a permanently damp, humus-rich 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]
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Other information
Extra information
There seems to be no basis for records of this species from Fiji and the New Hebrides. Lord Howe plants have recently been separated as a distinct endemic species Gahnia howense R.O.Gardner.
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for March 2009 for the full story.
Etymology
gahnia: After Gahn
xanthocarpa: The specific epithet xanthocarpa literally 'yellow-fruit' is inappropriate and was given by accident because the type material is of a specimen J.D. Hooker did not realise was bearing immature nuts which in this species are bright yellow. When the nuts of this species mature they are diagnostically dark glossy black.
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.
GAHXAN
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
Auckland: 2025 | Regionally Not Threatened | Qualifiers: DPS, DPT
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Auckland conservation status information is sourced from the “Conservation status of vascular plant species in Tāmaki Makaurau / Auckland” Simpkins E et al. (2025) report.
Referencing and citations
References and further reading
Gardner RO. 1995. Identifying Gahnia setifolia and G. xanthocarpa. Auckland Botanical Society Journal 50: 82–83.
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.