Hydrilla

Hydrilla is a submerged, rooted perennial that can grow to water depths of 9 metres, forming dense stands.

Description

• Stems are green and up to 3 metres long, either creeping or erect.

• Leaves are in whorls around the stem (typically four), serrated and have spines on the underside midrib. They are green but often have a reddish colour.

• Flowers are white, small and occur in the leaf bases during summer.

  Seeds are not set in New Zealand.

• Habitats include lakes, ponds, canals, and slow-moving streams.

What you need to know

Hydrilla forms dense mats, displacing native vegetation and impeding waterways and recreational activities.

Management approach

Hydrilla 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 hydrilla yourself. Report sightings to the MPI on Exotic Pest Hotline at 0800 80 99 66 or the online reporting form.