Entire marshwort

Entire marshwort is a perennial, bottom-rooted, aquatic herb with bright yellow flowers. It outcompetes native vegetation and can block access to waterways.

Description

• Stems are long, branched and creep below the water's surface
• Leaves are floating, heart-shaped, and less than 15cm in diameter. They are green, with purple undersides and scalloped margins.
• Flowers are yellow, either singly or in clusters on emergent stalks, and have fringed petals.
• Seed capsules are green, flattened and contain many hairy-edged seeds.
• Seeds are dispersed by water and waterfowl. Human-mediated dispersal through deliberate plantings, ornamental pond escapes and movement of contaminated boats and equipment.
• Habitats include rivers, lakes, ponds, reservoirs, wetlands, dams, and ditches.

What you need to know

Potential to form dense mats, outcompeting native vegetation, and impeding access to waterways.

Management approach

This is a declared pest managed under the Canterbury Regional Management Plan 2018 – 2038 (PDF file, 10.6MB) within the eradication programme.

Eradication

Pests in the eradication programme are present in low numbers or have limited distribution within Waitaha/Canterbury and eradication is feasible.

The community should make us aware of any entire marshwort plants in Waitaha/Canterbury. We will work with affected landowners to undertake control of entire marshwort.

Entire marshwort is declared an unwanted organism by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.

These species pose a high risk to our environment, economy, recreation, and cultural values.

Rules

Any species declared a pest cannot be sold or be in a place where plants are being sold. Pest plants cannot be propagated, bred, multiplied, communicated, released, caused to be released, or otherwise spread.

Control

Do not attempt to undertake control of entire marshwort yourself. Report any sightings to us.

If you've been in a waterway and plan to move to another within 48 hours, you must clean all your gear that has been wet using the 'Check, Clean, Dry' method.

It's vital that everyone uses the Check, Clean, Dry method on all equipment and vessels to stop freshwater pests.