Giant Hogweed

(Heracleum mantegazzianum)

Flowering stalk of Giant Hogweed, photo: Leslie J Mehrhoff

Status of giant hogweed in Tasmania

  • Giant hogweed is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of giant hogweed are prohibited in Tasmania.
  • The legal responsibilities of landholders and other stakeholders in dealing with giant hogweed are laid out in the Statutory Management Plan for Giant Hogweed.

What does giant hogweed look like?

  • Giant hogweed is an erect perennial (long-lived) herb which is distinguished by its size; the weed can grow to 3.5 metres when in flower, but can sometimes reach 7 metres in height. The stems are stout, hollow, with purple blotches. The leaves are large and deeply incised, resembling rhubarb leaves, and may grow to more than a metre in breadth. The undersides of the leaves are densely hairy. The flowers occur in broad, flat topped flower heads, and produce large dry fruits. The roots are tuberous and spreading and give rise to new buds each year.
  • Giant hogweed produces the first flowering stalk in its third, fourth or fifth year. After setting seed over summer, the plant dies in the following autumn.
  • Spread is by seed, and by buds formed on the crown and tuberous roots. Seed is spread by moving water, birds, and via the ornamental plant trade, dumping of garden waste and the spice trade.

Giant Hogweed, photo: Terry English

Image top: Flowering stalk of Giant Hogweed, © Leslie J Mehrhoff.
Image above: Giant Hogweed, © Terry English.

Impacts of giant hogweed

  • Giant hogweed is a weed of natural areas including riparian (riverside) habitats, roadsides and amenity areas. The weed is also toxic to humans and the sap can cause severe photo-sensitivity of the skin.

Where does giant hogweed occur?

  • Giant hogweed is a native of south west Asia and the Caucasus mountains. Giant hogweed has not naturalised on mainland Australia.
  • Giant hogweed has not naturalised in Tasmania. Giant hogweed has been recorded near Devonport in northern Tasmania, but appears to have been eradicated.

What you need to do

  • If you locate giant hogweed anywhere in Tasmania, or if you find a plant that you think could be giant hogweed, immediately contact Biosecurity Tasmania on 03 6165 3777 to report this weed.
See also
Statutory Management Plan for Giant Hogweed
Weed Links and Resources

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