Skip to main content


Weed Habitat 

  • Spreads rapidly along roadsides and railway lines.
  • It invades pastures and annual crops.
  • And is also invasive in less-disturbed woodland habitats.


  • An annual to short-lived perennial herb, usually growing from 40-80cm tall, but can grow to 1meter.
  • Flowers throughout the year, but most commonly after onset of wet season.
  • Flowers are an intense lilac-blue colour. (Which can be confused with “bluetops”)
  • Leaves are hairy and toothed along edges. Crushed leaves emit a sharp, unpleasant aroma.
  • Each plant produces hundreds or even thousands of small black seeds.

Eupatorium catariumEupatorium catariumEupatorium catarium


Plant Type

Leaf Arrangement

Other weed identifiers

Plant Life Cycle

Weed Declaration

Currently not declared however under the Biosecurity Act 2014 you still have an obligation to prevent or minimise a biosecurity risk posed by a pest.

Weed Spread