fennel-leaved pondweed, sago pondweed
Potamogeton pectinatus L., Coleogeton pectinatus (L.) D.H.Les et R.R.Haynes comb. inval.
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 = 78
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 | At Risk – Naturally Uncommon | Qualifiers: SO, Sp
Previous conservation statuses
2012 | At Risk – Naturally Uncommon | Qualifiers: PD, SO, Sp
2009 | At Risk – Naturally Uncommon | Qualifiers: DP
2004 | Sparse
Indigenous to New Zealand where it has been collected from the North, South and Chatham Islands. A cosmopolitan species known from throughout the world. No critical study on its worldwide variation seems to have been done.
Usually in brackish water, such as in slow moving tidal streams or lagoons, but also found in shallow lowland pools.
Wetland plant indicator status rating
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Aquatic rhizomatous herb. Rhizomes forming extensive networks in soft sediment, forming swollen bulb-like buds in autumn. Branches numerous, slender, delicate (rather brittle), 0.1-3 m or more long. Stipulate, with stipules fused to leaf base, forming a sheathing ligulate stem for 10-40 mm, the free portion (ligule) membraneous, 5 mm long. Leaves all submersed, 50-120 x 1 mm, dark green to brown-green, entire, narrow-linear (with transverse veins visible), tapering to an acute, membraneous tip. Peduncles slender, of varying length. Inflorescence a discontinuous brown spike 20-40 mm, with the lower flower clusters (whorls) well separated. Fruit, an achene 3 x 2.5 mm, light pinkish brown, turgid and rounded, without keel or beak.
Most likely to be confused with Ruppia spp. with which it often grows and from whose species it can be distinguished by the ligulate acute-tipped leaves, tuberous stems, and spicate inflorescences.
January - February
January - March
Difficult and should not be removed from the wild.
Probably more overlooked than actually threatened. Nevertheless there is some evidence that this species has declined for sites where it was formerly common over the least 20 or so years, and it remains absent from large stretches of apparently suitable habitat where it was once known 100 or more years ago. The main threat seems to be wetland modification and or drainage, particularly of those brackish wetland systems, or where streams and rivers enter the sea. However, the species can survive some modification and has even been collected in recently established channels, and within pools of water on the floor of gravel quarrys. Thus this species may prove to be naturally uncommon rather than genuinely declining. Further field survey is needed to clarify its exact status.
Where To Buy
Not commercially available.
The genus Stuckenia was erected in 1912. It differs from Potamogeton by the long stipular sheaths, tubular leaves with air channels bordering the midrib, flexuous peduncles, hydrophilous pollination and a hexaploid chromosome number (x = 13). Submerged leaves of Stuckenia are characteristically opaque and somewhat turgid. Stuckenia is further segregated from Potamogeton and Groenlandia by the fact that it never forms hybrids with either. Stuckenia pectinata is known to have aneuploids but the one New Zealand count known is not aneuploid and is typical of the species.
Fact sheet prepared for NZPCN by P.J. de Lange (January 2006). 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): Stuckenia pectinata Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/stuckenia-pectinata/ (Date website was queried)