Potamogeton perfoliatus
NPPA pest plant
Common names
clasped pondweed
Biostatus
Exotic
Conservation status
Not applicable
Category
Vascular
Structural class
Herbs - Monocots
Simplified description
Submerged aquatic plant that has green to red/brown leaves arranged alternately on stems, with the base of the leaves ‘clasping’ the stem. The leaves are up to 7cm long and 4cm wide with undulating margins, distinct longitudinal veins and finer transverse ones.
Flower colours
Green
Detailed description
Entirely submerged, bottom-rooting, normally perennial. Slender rhizomes and roots. The stems are up to 2m long, and the leaves clasp the stem. Alternate leaves are narrow to broadly ovate and greater the 6mm wide (although variable in size), green to red/brown in colour, thin and translucent, with undulating margins and many longitudinal veins and finer transverse venation. The inflorescence spike is short (1 to 2 cm long) when in fruit. Flowers small, green, on dense spikes up to 3 cm long at water surface. The fruit are 2.5 to 3 cm long, olive-green and smooth, convex on the ventral side and semi-circular on the dorsal. The keel is faint, as are 2 lateral ridges on the dorsal side and the beak is very short.
Similar taxa
Potamogeton perfoliatus can be distinguished from all other potamogetons by the way the leaf clasps the stem.
Distribution
Eradicated, only known from three sites, near Lakes Wakatipu and Hayes, Otago and Christchurch.
Habitat
Moderate flowing to still water bodies.
Detailed taxonomy
Genus
Family
Endemic genus
No
Endemic family
No
Ecology
Flowering
November - January
Fruiting
Not seen in New Zealand
Year naturalised
1996
Origin
Native to Central and North America, Eurasia, Africa and Australia
Reason for introduction
Ornamental pond and aquarium plant
Tolerances
Tolerant of sandy to muddy sedinments, still to fast flowing , fresh or brackish water.
Control techniques
Notify Ministry for Primary Industries if found.
Life cycle and dispersal
Reproduces by stem fragments and seeds. Dispersed by water, people liberating fish, possibly birds.
Other information
Etymology
potamogeton: River dweller
National Pest Plant Accord species
This plant is listed in the 2020 National Pest Plant Accord. The National Pest Plant Accord (NPPA) is an agreement to prevent the sale and/or distribution of specified pest plants where either formal or casual horticultural trade is the most significant way of spreading the plant in New Zealand. For up to date information and an electronic copy of the 2020 Pest Plant Accord manual (including plant information and images) visit the MPI website.
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.
Aston, H (1977). Aquatic plants of Australia. Melbourne University Press, 367pp.; Sculthorpe (1967) the biology of aquatic vascular plants. Edward Arnold Press, London.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).