Aquatic Invasives

Aquatic Invasives List

  • Red water fern; Rooiwatervaring

    Azolla filiculoides

    Perennial, mat-forming, free-floating aquatic fern 25 – 35 mm long.

    Leaves: Silvery-green, turning reddish-brown or purplish in winter; almost circular with blunt tips, loose alternate branching pattern.
    Roots: Fine laterals are absent.

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  • Parrot’s feather; Waterduisendblaar

    Myriophyllum aquaticum

    Growth form: Rooted aquatic plant with emergent, leafy shoots Leaves: Pale green, feather-like, arranged in whorls of 4 – 6. Flowers: Cream, inconspicuous, May – September.

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  • Pickerel weed; Jongsnoekkruid

    Pontederia cordata

    Growth form: Perennial, rooted aquatic plant, 1- 2 m high.
    Leaves: Light, yellowish green, one per stem, 230 mm long and 70 mm wide, long, stem-clasping petioles; heart-shaped, margins entire.
    Flowers: Blue, hairy, upper petal with yellow blotch in centre, glandular in spikes 50 – 150 mm long, September to June.
    Fruit: None seen in South Africa, sterile.
    Stems: Erect, emergent, horizontal rhizome, forming colonies.

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  • Water hyacinth; Waterhiasint

    Eichhornia crassipes

    Growth form: Perennial, mat-forming aquatic plant, free-floating, but can become anchored in shallow water; it is usually 100 – 200 mm high, but can grow up to 1 m when growing in dense mats.
    Leaves: Shiny dark green, arranged in basal rosettes with distinctive swollen bladder-like petioles.
    Flowers: Pale blue or violet; about 50mm across and occur in 8 – 10 flowered spikes; the upper petals have prominent dark blue, yellow-centred patches, November – April.
    Fruit: Capsules with very fine seed.
    Roots: Long and feathery.

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  • Watercress; Bronkors, Sterkkos

    Nasturtium officinale

    Growth form: perennial, mat-forming, rooted aquatic plant.
    Leaves: Bright green, pinnate with 3-11 leaflets, up to 40 mm long, margins entire, somewhat fleshy.
    Flowers: White, 5 mm long, in terminal elongated racemes, September to March.
    Fruit: Brown, two-valved, cylindrical, short beak-like tip up to 20 mm long.
    Stems: Hollow, erect, up to 1m long, rooting at the nodes.

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  • Yellow water lily; Geelwaterlelie

    Nymphaea mexicana

    Growth form: Perennial, rooted aquatic plant with floating leaves.

    Flowers: Pale to bright yellow, 80 – 180 mm across, emergent or floating, open during the day, fragrant. Pointed and star-like petals with greenish-yellow sepals. Flowering period: Nov-Feb.

    Fruit/seeds: Green berries which grow underwater.

    Leaves: Upper surface of the leaves are green, blotched with brown mostly while leaves are young, lower leaf surface green or pinkish-red with reddish blotches, leaf margins are generally wavy and upturned.

    Rhizomes & roots: Stout knobbly rhizomes connected by stolons, roots are long, pale and spongy.

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