Alligator weed

Alligator weed is a low-growing non-woody perennial plant. It is able to grow on both land and on water where it forms dense floating mats.

Description

• Long horizontal stems (stolons), up to 10m long that are hollow and often reddish in colour that root at nodes.

• Leaves are dark green and waxy.

• Flowers are clusters of papery white clover-like. Flowering from December to March.

• No fruit or seeds are produced in New Zealand. Instead, alligator weed easily establishes and spreads aggressively from the smallest of stem fragments.

• Habitats include land and water: still or slow-moving water bodies, pasture, cropland, and gardens.

What you need to know

Alters aquatic habitat structure and reduces native plant cover and diversity in wetlands and water body margins. Displaces valuable pasture species, blocks drainage channels, and exacerbates flooding on farmland. It is toxic to livestock.

Management approach

Alligator weed 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 alligator weed 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.