Nymphoides geminata

Marshwort

Family: Menyanthaceae

Origin: Australia

Marshwort growing in colourful pot.
Forms thick mats smothering native aquatic plants. Grows in ponds and streams and can block waterways and cause flooding.
Photo credit: M. Fagg, Australian National Botanic Gardens website

Regional Pest Management Plan (RPMP) status

  • Whole region — Eradication
  • National Pest Plant Accord Species

View more about the RPMP statuses

General description

Perennial water lily. Stolons are long and float near surface. Leaves are floating, heart-shaped and < 10 cm in diameter. Flowers are yellow with fringed petal and corolla margins, < 3.5 cm in diameter and borne on long stalks above the water’s surface in November – April.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell marshwort. As marshwort is a National Pest Plant Accord species, these restrictions apply within the Auckland region and across the whole of New Zealand.
  • You must not plant marshwort within the Auckland region.

Auckland Council will control marshwort at all sites where it is known to occur.

If you see marshwort anywhere in the Auckland region, please report it to Auckland Council at pestfree@aucklandcouncil.govt.nz.

Habitats

Still or slow-moving freshwater bodies.

Dispersal

Vegetative spread from stem and leaf fragments. Human-mediated dispersal through deliberate plantings.

Impact on environment

Forms thick mats, smothering vegetation, impeding drainage, and interfering with recreational activities. Potential to impact on the mauri of wai māori.

Control

Recommended approaches

Do not attempt to undertake control of this species. Please report to Auckland Council.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Marshwort growing in black tub.
An aquatic water lily from Australia that produces floating leaves. Underwater stolons float near the surface ready to break away.
Photo credit: M. Fagg, Australian National Botanic Gardens website