Scirpus polystachyus
Biostatus
Native
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 | Non-resident Native – Coloniser | Qualifiers: SO
Category
Vascular
Structural class
Sedges
Detailed description
Semi-aquatic to terrestrial summer green sedge forming robust leafy clumps up to 1.8 m tall. Stems more or less triquetrous, basally very leafy, with 3–5–(8) evenly spaced, cauline leaves. Leaves numerous, much < stems, 0.4–0.8 m × 5–8 mm, basally channelled but becoming flattened in upper half, strongly keeled, margins and keel finely scabrid; sheaths light reddish-brown, lustrous. Inflorescence a terminal compound, irregular, fan-shaped, umbel bearing many unequal erect rays; secondary rays slender, more or less drooping at maturity; leaf-liek bracts c. 3, > inflorescence, upper bracts dark brown, strongly nerved. Spikelets more or less 4 mm long, ovate, in clusters of 2–5 at tips of rays. Glumes more or less 1.5 mm long, light brown to live, membranous, much darker towards apex, midrib thickened, not excurrent. Hypogynous bristles many, filiform, much > nut, folded, twisted or spiralled, very conspicuous at maturity. Stamens 3. Stigmas 3. Nut more or less 0.7 mm long, more or less trigonous but dorsal angle not well marked, cream.
Similar taxa
None. However, in its vegetative state it can be confused with Bolboschoenus spp. which differ by their bulbous root stock, distinctly triquetrous stems, and by the leaves evenly spaced from the stem base to the inflorescence. Flowering material is very different as Scirpus polystachyus has a distinctive, densely and many flowered, fan-shaped umbel, those of Bolboschoenus either lack rays or have up to 3 short rays bearing up to 4 spikelets, subtending by a sessile mass of 3–4 spikelets.
Distribution
Indigenous. In New Zealand known only on the West Coast of the South Island, mainly in wetland south of Hokitika to about Okarito. Its range is still expanding. Common in Australia.
Habitat
Coastal to low lying fertile to moderately acidic open wetlands, lake, pond and slow flowing stream margins. Usually in well lighted places, often with its basalt stems and rhizomes immersed in water.
Threats
Not apparent threats but very localised in its distribution. Because the first gatherings were made from near plantation forestry this species has been regarded as a weed introduced from Australia (Healy & Edgar 1980). The alternative, that it naturally arrived here by wind or avian dispersal was not considered at the time. This species has seeds suited to bird dispersal and it is not associated with plantation forestry in Australia. Its distribution in New Zealand overlaps with that of grey teal which feed in areas it frequents and are known to move between countries, so are a suitable seed vector. Therefore de Lange et al. (2009) treated it as a successful trans-Tasman colonist that while still uncommon is now actively spreading.
Detailed taxonomy
Genus
Family
Synonyms
None
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
September–February
Fruiting
December–June
Propagation technique
Grows easily from fresh seed and rooted pieces. Has some potential as a pond ornamental. Requires full sun to flourish
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]
FACW: Facultative Wetland
Usually is a hydrophyte but occasionally found in uplands (non-wetlands).
Other information
Where To Buy
Not commercially available
Chromosome number
2n = 60
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 | Non-resident Native – Coloniser | Qualifiers: DP, SO
2012 | Non-resident Native – Coloniser | Qualifiers: SO
2009 | Non-resident Native – Coloniser | Qualifiers: SO
2004 | Non-resident Native – Coloniser
Referencing and citations
References and further reading
de Lange PJ, Norton DA, Courtney SP, Heenan PB, Barkla JW, Cameron EK, Hitchmough RA, Townsend AJ. 2009. Threatened and uncommon plants of New Zealand (2008 revision). New Zealand Journal of Botany 47(1): 61–96. https://doi.org/10.1080/00288250909509794.
Healy AJ, Edgar E. 1980. Flora of New Zealand, Volume III. Adventive Cyperaceous, Petalous and Spathaceous Monocotyledons. Government Printer, Wellington, NZ. 220 p.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (30 August 2005). Description adapted from Healy & Edgar (1980) supplemented with details obtained from fresh plants and herbarium material by P.J. de Lange.
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): Scirpus polystachyus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/scirpus-polystachyus/ (Date website was queried)