Zostera muelleri subsp. novazelandica
Past favourite plant finalist
Common names
seagrass, eelgrass, nana, zostera, rimurehia
Biostatus
Native
Category
Vascular
Structural class
Herbs - Monocots
Detailed description
Grass-like plants of mud or sandy-silt shallow marine environments. Rhizomes compressed 1–2 mm diameter, widely creeping, rooting at nodes; internodes 10–20 mm long. Leaf-sheath 20–40 mm long, becoming fibrous with age, the broad membranous margins inflexed and each terminating in an erect rounded auricle. Lamina 50–300 × 1–2 mm; primary nerves 3, interstitial nerves 4–6, cross veins usually at more or less regular, long intervals and mostly all extending from the median to marginal nerve, producing a pattern of distinctive long oblongs. Erect stems narrow, flattened, the subfloral peduncular internode 10–60 × 0.6–1.0 mm. Spathe-like sheath 15–25 × 2.0–2.5 mm (folded width), its margins squarely truncate at the apex and its terminating lamina 30–80 × 1.5–2.0 mm. Spadix often shorter than spathe; retinacula usually 3 on each side, broadly obliquely ovate 1.0–1.5 × 1.0 mm and 2.0–2.5 mm apart. Stamens and carpels closely packed, carpels rarely > 6 and anther-sacs about twice their number, all sloping obliquely inwards and upwards. Achene elliptic-oblong, 2.5 × 1.0 mm; seed smooth, yellow.
Similar taxa
None. Plants referred to Zostera capricorni in Flora II are merely larger forms of the same subspecies. The type of Z. capricorni is Australian and plants matching that type are not found in New Zealand.
Distribution
Indigenous. North Island, South Island and Stewart Island/Rakiura. Throughout southern and eastern Australia.
Habitat
Marine. Mostly submerged in estuaries where it is found on intertidal and subtidal flats of sandy mud. Often in channels or deep pools of water
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 | At Risk – Declining | Qualifiers: EF, SO
Threats
Eelgrass communities are declining throughout their range because of widespread siltation and increasingly poor water quality.
Detailed taxonomy
Family
Synonyms
Z. novazelandica Setch., Zostera muelleri Irmisch.ex Asch.; Zostera muelleri subsp. novaezelandica (Setch.) S.W.L.Jacobs orth. var.
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–February
Fruiting
January–February
Propagation technique
Easily grown in saltwater tanks but otherwise difficult. Plants can be easily propagated through division.
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]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
Where To Buy
Not commerically available.
Etymology
zostera: Girdle or belt
muelleri: Named after Baron Ferdinand von Mueller, 19th century German/Australian botanist and founder of the National Herbarium of Victoria
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.
ZOSMSN
Chromosome number
2n = 24
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 | At Risk – Declining | Qualifiers: EF, SO
2012 | At Risk – Declining | Qualifiers: SO
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
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.
Otago: 2024 | At Risk – Regionally Naturally Uncommon | Qualifiers: CI, DPS, DPT, EF, PF, RR
Referencing and citations
References and further reading
Moore LB, Edgar E. 1970. Flora of New Zealand, Volume II. Indigenous Tracheophyta: Monocotyledones except Gramineae. Government Printer, Wellington, NZ. 354 p.
Attribution
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.