Vallisneria australis

Notifiable Organism, Unwanted Organism (as synonym), National Pest Plant Accord

• Eel grass

• Scientific Name: Vallisneria australis
• Origin: Native to Australia
• Type: Weed
• Plant Life-form Type: Submerged
• Taxonomy: S.W.L.Jacobs & Les
• Presence: Locally naturalised in North Island and Marlborough in the South Island, first record 1897 in Lake Pupuke, Auckland.
• Habitat: Moderately fast flowing to still water bodies.
• Notes: A potentially important submerged weed; poor dispersal capacity has limited current spread.
• Propagation: Spread by stolon fragmentation. There is no evidence of viable seed production in New Zealand
• Features: The leaves are thick and strap-like and arise from long creeping stems. Leaves are up to 3 m long and between 0.5 and 5 cm wide. The leaf tips (when not browsed) are obtuse to acute, with fine toothed margins towards the apex. Male plants are only known from Lake Pupuke, with female plants also confirmed there. Male flowers (a translucent sheath surrounding many tiny yellow flowers) being produced in the leaf bases. All other naturalised populations are female, the female flowers are green and cylindrical borne on long, often spiral, filamentous stalks arising in the leaf bases and extending to the waters surface.
• Source: TIFBIS
• Synonym: Vallisneria spiralis, V. gigantea, V. americana
• Regional: Regional Pest Management Strategy: MBH, NTL, WGN, MWT, AUK, WKO.