Bitter weed

Native to south-eastern USA and Mexico, bitter weed is a compact annual with small yellow flowers.

Bitter weed is poisonous to livestock and competes with pasture and native vegetation. In Queensland, it has been found at only 1 location, near Mount Tarampa in the Lockyer Valley.

Scientific name

Helenium amarum

Description

  • Annual herb up to 60cm tall, compact and bushy under favourable conditions.
  • Stems are smooth and branching with numerous leaves.
  • Leaves are smooth, narrow, thread-like, light green to gray-blue.
  • Flowers are yellow, daisy-like, about 2cm in diameter.
  • Unnoticed when competing with other plants, producing a single flower on plants as small as 5cm tall.

Habitat

  • Prefers open fields, roadsides and disturbed areas in subhumid, warm temperate and subtropical areas where annual rainfall does not exceed 1,000mm.

Distribution in Queensland

  • Only known to exist at a single location near Mt Tarampa in Lockyer Valley in South East Queensland.

Life cycle

  • Flowers mostly over spring and summer.
  • Scented flowers are pollinated by insects such as bees and butterflies.
  • Mature seeds are non-dormant and germinate readily in sunlight.

Affected animals

  • sheep; horses; cattle

Impacts

Environmental

  • Competes with native vegetation.

Economic

  • Potential weed of pastures.
  • Poisonous to stock, including sheep, horses and cattle.
  • Taints milk of dairy cattle.

How it is spread

  • Seeds in hay, silage and on vehicles.

Control

Physical control

  • Hand-pull, ensuring entire root system is pulled up.

Herbicide control

  • Broad-leaf herbicides such as 2,4-D or Grazon P+D® can be effective.

Biological control

  • No known biological control agents.

Declaration details

  • This is not a declared species under the Land Protection (Pest and State Route Management) Act 2002 but may be declared under other legislation or local government law.

More information

Contact us

Call your local government office, or Biosecurity Queensland on 13 25 23.

Last updated
25 November 2015

Contact

General enquiries 13 25 23

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