Heracleum mantegazzianum

Giant hogweed

Also known as:

Cow parsnip, giant carrot

Family: Apiaceae

Origin: Asia

Tall stalks of giant hogweed.
Giant hogweed flowers are formed on tall stalks with umbrella-like clusters of white flowers.
Photo credit: Elaine Iddon

Regional Pest Management Plan (RPMP) status

  • National Pest Plant Accord Species
  • Whole region — Exclusion

View more about the RPMP statuses

General description

Biennial or perennial megaherb < 5 m tall. Taproot is fibrous. Stems are hollow, finely haired and covered in red/purple spots. Leaves are compound, large, < 50 cm across and serrated. Flowers are small, green/white and borne in umbels.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell giant hogweed. As giant hogweed 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 giant hogweed within the Auckland region.

If you see giant hogweed anywhere in the Auckland region, please report it to Auckland Council at pestfree@aucklandcouncil.govt.nz.

Habitats

Riparian and forest margins, roadsides, flood plains, drains.

Dispersal

Seeds dispersed by water, gravity and wind. Human-mediated dispersal through movement of contaminated soil and deliberate plantings.

Impact on environment

Forms dense infestations, suppressing native vegetation and exposing banks to erosion during periods of seasonal dieback. Can cause photodermatitis in humans, possibly requiring medical treatment.

Control

Recommended approaches

Do not attempt to undertake control of this species. Please report to Auckland Council.

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

The flowers of the giant hogweed.
One plant can produce up to 50,000 seeds.
Photo credit: Elaine Iddon