Parthenium

Scientific name: Parthenium hysterophorus
Declaration status: Class A and Class C

Parthenium is a Weed of National Significance.

For more information go to the Weeds of National Significance website.

Parthenium weed is a native of Central and South America.

It was first recorded in Australia in 1955, and has since spread through central Queensland and New South Wales where it is now well established.

In 1977 parthenium was discovered in the Northern Territory (NT) along Elsey Creek in the Mataranka district.

The infestation had spread 8km downstream from the Roper Highway.

The Weed Management Branch conducted an intensive eradication program which was successful.

Smaller infestations have been reported and controlled in the Katherine and Borroloola areas. Parthenium weed was found at the Tennant Creek stockyards in 2010.

There are currently no other known parthenium plants in the NT.

Impact

Parthenium is a major problem in rangelands and cropping areas of Queensland costing farmers and graziers more than $22 million a year in reduced production and increased management costs.

Parthenium can have all of the following impacts:

  • degrades pastures, increasing production costs and decreasing productivity
  • toxic to stock and humans
  • can cause allergic skin reactions in people.
  • may take up to 20 years for allergic symptoms to show
  • taints meat from livestock that eat it.

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

  • fast-maturing, branching annual herb, erect stem up to 2m high
  • becomes woody with age
  • pale green and lobed leaves covered with soft, fine hairs
  • small and white flowers grow on the stem tips 4mm across in five distinct corners
  • each flower produces four or five seeds
  • seeds are black and wedge-shaped 2mm long with thin white scales and can have up to 100,000 seeds produced per plant.
Parthenium - habitParthenium - stemsParthenium - leavesParthenium - flowersParthenium - fruit and seeds

For more information get the parthenium identification fact sheet (1.3 mb).

If you are unsure, contact the Weed Management Branch.

Control

If you think you may have seen parthenium, or have this weed on your property, do not attempt to control it.

Contact the Weed Management Branch immediately for assistance.

Parthenium is on the alert list for environmental weeds. This is a list of weeds that threaten biodiversity and cause other environmental damage.

Spread

Parthenium can spread rapidly if introduced into an area. It produces large quantities of seeds, which contaminate harvested material including hay, vehicles, machinery and livestock, all which help with spread.

Spread prevention

Vehicles and produce coming from areas in Queensland that are affected by parthenium should be checked and/or cleaned before entering the NT and individual properties.

Wash down areas should be closely monitored for parthenium plants.

Last updated: 12 May 2018