Vascular – Native
Herbs - Monocots
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.
2n = 28
Current conservation status
The threat classification status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – a suggested threat classification status has not been assessed by the NZTCS panel.
2017 | Not Threatened
Previous conservation statuses
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Endemic. New Zealand: North, South and Stewart Islands
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.
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).
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
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.
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.
December - March
January - April
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
potamogeton: River dweller
suboblongus: Nearly oblong
Fact sheet prepared for NZPCN by P.J. de Lange (16 February 2012). Description adapted from Moore & Edgar (1970).
References and further reading
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.
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)