Hydrilla verticillata

Hydrilla

Family: Hydrocharitaceae

Origin: Africa, Australia, Eurasia

Hydrilla plant underwater.
Grows on the bottom of ponds with stems growing as long as 3m. Forms dense mats that can clog ponds and streams..
Photo credit: Weedbusters

Regional Pest Management Plan (RPMP) status

  • National Pest Plant Accord Species

View more about the RPMP statuses

General description

Submerged bottom-rooted perennial aquatic. Stems are branched and < 3 m long. Leaves are in whorls around the stem, serrated and have spines on the underside midrib. Flowers are small and transparent with red streaks.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell hydrilla. As hydrilla is a National Pest Plant Accord species, these restrictions apply within the Auckland region and across the whole of New Zealand.

If you see hydrilla anywhere, you must report it to the Ministry of Primary Industries on 0800 80 99 66.

Habitats

Lakes, ponds, canals, slow-moving streams.

Dispersal

Seeds not set in New Zealand. Vegetative spread from tubers, turions, rhizomes and stem fragments, dispersed by water and contamination of livestock. Human-mediated dispersal through movement of contaminated boats, equipment and machinery.

Impact on environment

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

Control

Site management - recommended approaches

Do not attempt to undertake control of this species. Please report to the Ministry for Primary Industries.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.