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  • Hydrilla verticillata

      Notifiable Organism, Unwanted Organism, National Interest Pest Response (national eradication programme instigated 2008), National Pest Plant Accord
    • Scientific Name: Hydrilla verticillata
    • Origin: Introduced plant. Native to Asia, Europe, Africa and Australia
    • Type: Weed
    • Plant Life-form Type: Submerged
    • Taxonomy: (L.f.) Royle
    • Presence: Locally naturalised in Hawkes Bay, first record from Lake Tutira in1963
    • Habitat: Only known from lake environments in New Zealand, but grows in flowing waters in other countries
    • Temperature (°C): Oct-28
    • pH range: 6.5 - 7.5
    • Hardness (ppm): 50 - 200
    • Light: Medium
    • Difficulty: Easy
    • Notes: A potentially major submerged weed in New Zealand (more competitive than hornwort) and the worst aquatic weed in the USA. Grows in all temperate sub tropical and tropical zones. The stem can be several metres long and profusely branched. Is a pest plant that causes much havoc in Lake Tutira Hawkes Bay.
    • Propagation: The most common method of spread is from stem fragments. Hydrilla also spreads via tubers and turions, underground rhizomes, and above ground stolons. Banned - Illegal to propagate
    • Features: The leaves are 6-20mm long and occur in whorls of 3-10, often varying greatly on the same shoot. They generally have sharp teeth along the leaf margin.
    • Source: TIFBIS
    • Regional: Regional Pest Management Strategy: NTL, AUK, HKB, WKO.
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