Mexican water lily
Origin: Mexico, North America
Regional Pest Management Plan (RPMP) status
- National Pest Plant Accord Species
- Whole region — Sustained control
Perennial, bottom-rooted aquatic herb. Rhizomes are stout and erect. Stolons are creeping and tuberous. Leaves are floating, round, heart-shaped, < 20 cm in diameter and green with brown flecks on top, with a pink/purple underside. Flowers are yellow, < 15 cm in diameter and borne above the water surface in October – December. Fruit is spherical to ovoid, < 2.5 cm diameter and ripens in summer – autumn.
What you need to know
To help protect our environment:
- You must not breed, distribute, release or sell Mexican water lily. As Mexican water lily 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 Mexican water lily within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
- You must destroy any Mexican water lily on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.
Still and slow-moving freshwater bodies.
Seeds dispersed by water movement. Vegetative spread from rhizomes and tubers, dispersed by water. Human-mediated dispersal through deliberate plantings.
Impact on environment
Forms dense mats and may displace submerged aquatic plants. Reduces dissolved oxygen levels, affecting fish, zooplankton and other native species.
Follow up treated areas 3 times per year.
Method: Mechanical removal or pull-out.
Plant parts requiring disposal: All parts.
Disposal options: Remove to greenwaste or landfill if practical.
Biocontrol is currently not available for this species.
Community agrichemical control recommendations
Certified Handler/Experienced agrichemical user: Foliar spray emergent foliage with 300ml glyphosate green per 10L of water.
Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.