What does it look like?
Eel grass is a submerged, bottom-rooted freshwater plant, found in streams, drains, wetlands, lake margins, ponds and aquariums. It produces long, thick, strap-like leaves that are up to 3 metres long. Leaves are light green to brown, slimy to the touch and don't emerge above the surface of the water.
Both male and female plants exist. Male flowers consist of large pollen-filled sacs produced at the base of mature plants. Female flowers are small and green and produced on the end of a very long, spirally coiled stalk that can extend to the water’s surface. There is no evidence of viable seed production occurring in New Zealand, but it spreads by rhizomes or broken off root fragments.
Why is it a problem?
Eel grass forms dense beds that can grow to a depth of 9 metres, out-competing and displacing native plants. In New Zealand, it’s generally spread through intentional planting. It can block waterways, leading to sediment build-up and flooding, and may affect recreational activities, impede navigation and obstruct water out-takes.
Control methods
For control advice, please contact us on 06 835 9200.
Related links
Management Programme
National Pest Plant Accord
All plants on MPI's National Pest Plant Accord (NPPA) are unwanted organisms under the Biosecurity Act 1993 whose formal or casual trade contributes significantly to their spread.
Plants on the Accord cannot legally be propagated, distributed, or sold in New Zealand. If allowed to spread further, these pest plants could seriously damage our economy and environment.
Unwanted Organism
An unwanted organism is any organism that's capable of causing harm to natural or physical resources (like forests and waterways) or human health. A number of introduced pests in New Zealand are classed as unwanted.
More informationRules
Section 26ZM of the Conservation Act (1987)
In accordance with the Conservation Act 1987 section 26ZM, no person shall transfer live aquatic life or release live aquatic life into any freshwater. This includes native or introduced fish, plants, and invertebrates. The taking and holding of some organisms requires a special permit from MPI.
More informationTaxonomies
FamilyHydrocharitaceae
TypePlants
GroupSubmerged
HabitatFreshwater
Management ProgrammeNational Pest Plant AccordUnwanted Organism
