Marshwort

Also known as:
Entire Marshwort
Family:
Menyanthaceae
Origin:
Australia

General description

Robust bottom-rooted perennial, which has long, branched running stems that sit just below the water surface and extend for several metres across. Bright green heart shaped leaves with pinkish undersides <10cm, smaller than other water lilies. Distinctive bright yellow, 5 petalled fringed flowers (Nov-Apr) in pairs on long stems. Very similar to Nymphoides peltata, distinguished by more oval leaf-shape & lack of red markings on leaves.

Wetlands, swamps, drains, ponds, dams. Prefers slow flowing freshwater <2.5m, survives in damp mud. Tolerates wide temperature range.

Detached stems & leaves grow roots. Spread by boats, fishing gear, machinery locally by running stems. No seed in NZ.

Dense vegetation blocks waterways, impeding drainage, disrupting recreational activities. Degrades water quality. Out-competes native species.

Site management

Regular follow up required.

Recommended approaches

1. Report it immediately to the Auckland Council Biosecurity team, who will arrange for its control at their expense.
2. Clear smaller infestations by hand.
3. Weedmat, 6 months.
4. Spray emergent foliage (100ml glyphosate/10L, use glyphosate formulation approved for use over water). Repeat when necessary.

Caution: when using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.

Similar species

fringed water lily
Nymphoides peltata

Fringed water lily has leaves with scalloped margins.

water poppy
Hydrocleys nymphoides

Water poppy has an oval leaf with an inflated mid vein on the underside.

yellow water lily
Nuphar lutea

Yellow water lily has larger leaves and spongy stolons.

Mexican water lily
Nymphaea mexicana

Mexican water lily has a larger leaf with a definite main vein.

Search tags

RPMS status

Total Control - Whole Region
National Pest Plant Accord species - nationwide
marshwort - Main species image