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Brilliantaisia (Brillantaisia lamium)

Brilliantaisia is an introduced invasive weed in tropical Australia, with infestations also recorded around Brisbane. It can spread through moist, disturbed areas and form dense thickets that displace native vegetation.

Key facts

Type: Weed, herb.

Native to: Central and West Africa.

Established in: QLD.

Other names: Blue brilliantaisia.

Best time to act: Look for and treat plants while they are actively growing and before the cigar-shaped seed pods mature.

Identification

  • A coarse, branched herb that grows from about 20 cm to 2 m tall.
  • Leaves are opposite and heart-shaped, and the stems are hairy and square in cross-section.
  • Flowers are bright blue to purple.
  • Seed pods are long and cigar-shaped.

Where it grows

In Australia it grows in moist areas, including riparian and disturbed sites, in full sun or part shade.

Why it matters

  • Dense thickets can crowd out native vegetation.
  • Infestations can reduce food sources for wildlife.
  • It can spread quickly through riparian and disturbed areas.

How it spreads

  • It reproduces by seed.
  • Stem fragments can take root and establish new plants.

Control options

  • For small plants, remove them physically before they set seed, taking care to remove plant material and contain it so fragments cannot take root.
  • For larger infestations, use a herbicide registered or permitted for the target weed and site, strictly following the product label.
  • Near waterways, use only products approved for aquatic or riparian settings and prevent spray drift or contamination of water.
  • Revisit treated areas to check for regrowth and new seedlings; report new or expanding infestations to the relevant local council or Biosecurity Queensland.

Hygiene and washdown

  • Clean soil, seeds and plant fragments from boots, tools and machinery before leaving an infested site.
  • Contain removed plants and fragments for appropriate disposal, and avoid moving contaminated soil or plant material to clean areas.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)

Sources