Potamogeton crispus
Environmental Weed (2024)
Common names
curly pondweed
Biostatus
Exotic
Category
Vascular
Structural class
Herbs - Monocots
Simplified description
Submerged aquatic plant that has green to red/brown leaves arranged alternately on stems. the leaves are ca 10mm in width and up to 80 mm long with distinct wavy edges (hence the name ‘crispus’). Centre veins of the leaves are normally reddish.
Flower colours
Cream, Green
Detailed description
Entirely submerged, bottom-rooting, normally perennial. Slender rhizomes and roots. P. crispus has long branched stems, that feels slightly flattened (as opposed to round or cylindrical), with submerged leaves that are arranged alternately on the stem. The leaves are green to reddish brown, slightly translucent, about 10mm in width, and up to 80mm long. Leaf margins are markedly wavy and crimped, with fine teeth near the tip. Centre veins of the leaves are normally reddish. The inflorescence spike has few flowers. Flowers small, green, on spikes up to 1 cm long, 4 flat dark seeds. The fruit (achenes) are large (4mm) and thick, with a curved beak and a toothed (rounded toothed) dorsal keel. Turions or winter buds of hard scales formed by shortened, thickened leaves with broad and strongly toothed bases.
Similar taxa
Potamogeton ochreatus and P. cheesemanii. P. ochreatus has a straight edged leaf and a blunt leaf tip, whereas curled pondweed has a rounded leaf tip with crimped edges. It can be distinguished from P. cheesemanii by the submerged leaves, which are narrower and much more crimped in curled pondweed.
Distribution
Widely naturalised throughout New Zealand, rare in West Coast Region
Habitat
Moderately fast flowing to still water bodies.
Conservation status
Not applicable
Detailed taxonomy
Family
Potamogetonaceae
Ecology
Flowering
November, December, January
Fruiting
Autumn
Year naturalised
1940
Origin
Native to Europe, Asia, Africa and Australia.
Reason for introduction
Ornamental pond and aquarium plant
Tolerances
Tolerates brackish, flowing or still water, and grows to 10 m depth.
Control techniques
Not usually controlled in New Zealand, but may be controlled manually, or mechanically.
Life cycle and dispersal
Spread by seeds, stem fragments, rhizomes, or turions. Birds disperse seed, fragments, rhizomes and turions dispersed by contaminated machinery and water movement.
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
Environmental Weed (2024)
This plant is named in a list of 386 environmental weeds in New Zealand 2024 prepared by DOC. 759 candidate species were considered for inclusion on this new comprehensive list of environmental weeds in New Zealand. The species considered were drawn from published lists of weed species, lists of plants that must be reported or managed by law if observed, existing national and regional programmes and agreements for pest management, and species already managed by the Department of Conservation (DOC). Candidate species were then assessed to see if they were fully naturalised and whether they have more than minor impacts in natural ecosystems. Read the full report here.
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.
POTCRI
Referencing and citations
References and further reading
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Coffey BT, Clayton JS (1988). New Zealand water plants: a guide to plants found in New Zealand freshwaters. Ruakura Agricultural Cente. 65pp.
Aston, H (1977). Aquatic plants of Australia. Melbourne University Press, 367pp.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).