Potamogeton suboblongus
Common names
mud pondweed
Biostatus
Native
Category
Vascular
Structural class
Herbs - Monocots
Detailed description
Aquatic, submerged or floating, or ± semi-terrestrial on muddy ground and seepages, rhizomatous little-branched, perennial herb. Rhizomes usually buried in firm mud; leafy branches erect, usually simple, long or short, often rooted at leaf-bearing nodes. Stipules c.20–30 mm long, free, open, membranous and often conspicuous. Leaves weakly dimorphic, entire; lower leaves apparently not regularly submersed, similar to upper leaves, being somewhat more narrowly elliptic and with fewer, more obscure nerves than emergent leaves; upper and emergent leaves long- or short-petiolate, lamina 15–60 × 8–35 mm, broad-elliptic, rarely oval, subacute and sometimes shortly attenuate at tip, firm and opaque, longitudinal nerves 11–21 in all, usually several laterals emerging from midrib. Inflorescence a densely flowered spike, 10-20 mm long. Peduncles arising in axils of upper leaves, simple, stout, erect, standing well above leaves. Achenes c.2.0 × 1.5 mm, reddish when ripe, neither flattened nor strongly keeled, beak short but slightly curved.
Similar taxa
Distinguished from Potamogeton cheesemanii by the scarcely dimorphic foliage (i.e. only slight differences between submersed and emergent leaves), by the near absence of submersed leaves (these if present of similar size and shape to emergent foliage), by the broadly elliptic, subacute floating leaves, which have usually 6 or more nerves on either side of midrib; and by the swollen, reddish, not or only weakly keeled achenes.
Distribution
Endemic. New Zealand: North, South and Stewart Islands
Habitat
Coastal to subalpine, being mostly found in upper montane and subalpine areas in the northern part of its range. Potamogeton suboblongus is more commonly found in shallow, muddy hollows in forest, and colonising tarns and alpine soaks and pools which may partially dry out in summer.
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.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- 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
Potamogetonaceae
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December - March
Fruiting
January - April
Propagation technique
Easily grown from rooted pieces and fresh seed, An attractive plant for a small, shallow pond or damp, shaded hollow. In warmer, lowland areas this species prefers a cool site
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
Etymology
potamogeton: River dweller
suboblongus: Nearly oblong
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.
POTSUB
Chromosome number
2n = 28
Previous conservation statuses
2017 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Referencing and citations
References and further reading
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (16 February 2012). Description adapted from Moore & 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): Potamogeton suboblongus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/potamogeton-suboblongus/ (Date website was queried)