Africa, Australia, Eurasia

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.

Lakes, ponds, canals, slow-moving streams.

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.

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

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.

Similar species

Egeria densa

Egeria lacks toothed leaf margins.

southern naiad
Najas guadalupensis

S naiad's leaves are on short branches.

Lagarosiphon major

Lagarosiphon has alternate leaves and lacks the toothed leaf margins.

Search tags

RPMP status

National Pest Plant Accord Species
Hydrilla - Main species image