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   Potamogeton perfoliatus (aquatic plant)     
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      Potamogeton perfoliatus (Photo: Adrian Jones, IAN Image Library) - Click for full size
    Taxonomic name: Potamogeton perfoliatus L.
    Synonyms: Potamogeton amplexicaulis Kar., Potamogeton bupleuroides Fern., Potamogeton perfoliatus ssp. bupleuroides (Fern.) Hultén, Potamogeton perfoliatus var. bupleuroides (Fern.) Farw.
    Common names: claspingleaf pondweed, perfoliate pondweed, redhead grass
    Organism type: aquatic plant
    Potamogeton perfoliatus is a submerged aquatic plant that occurs in still and flowing freshwaters in temperate climates. It is known as clasped pondweed as the leaf bases perfoliate (are wrapped around the stem). This is one of the commonest pondweeds. All the leaves are under water; there are no floating leaves as in some other common Potamogeton species. It is common in lakes, ditches and slow rivers and streams, and is tolerant of quite a wide range of nutrient status.
    Description
    Potamogeton perfoliatus is one of the common pondweeds, rather robust, with the leaf bases wrapped around the stem. All the leaves grow under water and there are no floating leaves. Leaves are flat, oval-shaped, 2-6cm long, narrow (due to lack of light and calcium) but margins are slightly crisped (Farmer, 2003; MDNR, 2005). Plants have thicker, darker green foliage than do plants growing in deeper water (MDNR, 2005). Ailstock and Shafer (2004) state “reedgrass typically survives in winter by persistence of sparsely branched pale rhizomes embedded in the sediments. Inflorescences are variable but mostly consisting of 5-12 flowers with each consisting of 4 carpels which in turn contain a single ovule. Seed formation ranges from 20-48 seeds per inflorescence". Redhead grass has an extensive root and rhizome system that securely anchors the plant (MDNR, 2005).
    Similar Species
    Potamogeton crispus, Potamogeton praelongus, Potamogeton richardsonii

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    Occurs in:
    lakes, water courses
    Habitat description
    Potamogeton perfoliatus grows best on firm, muddy soils and in quiet water with slow-moving currrent (MDNR, 2003). The pond weed is indicative of a wide range of nutrient conditions and pH tolerance. However some are only found in moderately acid to moderately alkaline conditions. Habitat types: Fresh to brackish water; high pH; muddy, fine sediment; slow moving water; shallow water; and provides habitat for marine mammals.
    Uses
    Potamogeton perfoliatus is considered an excellent food source for waterfowl (MDNR, 2005). Seeds, stems, and rootstock are valuable source of food for redhead ducks, canvasbacks, mallards, black ducks, Canada geese and tundra swans. Provides habitat for many aquatic organisms.
    Geographical range
    Native range: Continental USA (ITIS. 2005). Europe.
    Known introduced range: Australia; New Zealand (Champion and Clayton, 2000).
    Introduction pathways to new locations
    For ornamental purposes: Potamogeton perfoliatus is reported present in New Zealand as being sold as an ornamental plant (Champion and Clayton, 2000).
    Pet/aquarium trade: Potamogeton perfoliatus is reported present in New Zealand as being sold as an ornamental plant (Champion and Clayton, 2000).
    Translocation of machinery/equipment: Stem fragments of the plant can be dispersed to other waterways by boats, trailers, nets and machinery (RNZIH, 2005).


    Local dispersal methods
    Boat: Stem fragments of the plant can be dispersed to other waterways by boats, trailers, nets and machinery (RNZIH, 2005).
    Consumption/excretion: The plant spreads by seed dispersed by waterfowl (RNZIH, 2005).
    For ornamental purposes (local): Potamogeton perfoliatus is reported present in New Zealand as being sold as an ornamental plant (Champion and Clayton, 2000).
    Translocation of machinery/equipment (local): Stem fragments of the plant can be dispersed to other waterways by boats, trailers, nets and machinery (RNZIH, 2005)..
    Management information
    Champion and Clayton (2001) Aquatic Plant Weed Risk Assessment Model classifies P. perfoliatus as a high risk species in New Zealand.
    Reproduction
    Reproduction is through a combination of vegetative or clonal offspring and those resulting from seeds (Ailstock and Shafer, 2004). Seeds are the most significant contributor to the reproductive potential of perennial species (Ailstock and Shafer, 2004). MDNR (2005) reports that "asexual reproduction occurs by formation of over-wintering, resting buds at the ends of rhizomes. Sexual reproduction regularly occurs in early to mid-summer. Spikes of tiny flowers emerge from leaf axils on ends of plant stems. Flower spikes extend above the water surface and the pollen is carried by wind. As fruits mature they sink below the surface where they release seeds".
    Reviewed by: Expert review underway: Susanne Wolfer Germany
    Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG) with support from the Terrestrial and Freshwater Biodiversity Information System (TFBIS) Programme (Copyright statement)
    Last Modified: Tuesday, 11 April 2006


ISSG Landcare Research NBII IUCN University of Auckland