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Leucaena (Leucaena leucocephala)

Introduced as fodder, leucaena can spread quickly when it is not heavily grazed or controlled. It forms dense thickets that outcompete native plants and can restrict movement of people and animals.

Key facts

Type: Weed, tree.

Native to: Central and South America.

Established in: QLD, NSW, WA, NT.

Other names: lead tree, coffee bush.

Identification

  • An erect shrub or tree, usually 2–8 m tall, but it can grow to 20 m.
  • Its fern-like leaves are divided twice into many small, hairless leaflets.
  • Creamy-white or greenish-white flowers form fluffy, round pom-poms, usually in summer.
  • Glossy brown, flattened pods grow in dense clusters and contain 10–25 seeds.
  • Young stems are green and covered in greyish hairs; older stems are smoother and greyish or greyish-brown, with raised spots.
  • Look-alike: Mimosa bush (Vachellia farnesiana) looks similar, but has pink pom-pom-like flowers and less dense foliage.

Where it grows

In Australia, leucaena is found on the North Coast and in the greater Sydney region, and grows in tropical and subtropical climates.

Why it matters

  • Dense stands can outcompete native plants and reduce habitat and food for native animals.
  • Thickets can restrict the movement of people and animals.
  • Young leaves contain mimosine, which can cause hair loss in some animals and slow weight gain in cattle, sheep and goats when it makes up more than about 30% of their diet.
  • Leaves, seeds and pods can poison livestock that have not been inoculated.

How it spreads

  • Leucaena produces seeds all year round; plants in Queensland have produced up to 17,600 seeds per year.
  • Seeds spread via birds, possums, rodents and cattle, and can travel short distances by wind or be carried by moving water.
  • Seeds can also spread in contaminated hay and in mud on vehicles and machinery.

Control options

  • Dig out small individual plants and remove all roots to prevent regrowth.
  • Use rotational and continuous grazing to keep bushes to a maximum height of 2 m; slash trees at 1 m high if they are getting too tall.
  • For chemical control, use registered herbicides by basal barking, cut-stump treatment or stem injection with capsules, following the product label.
  • Follow up after initial control by checking for and killing regrowth and new seedlings.

Hygiene and washdown

  • Avoid moving contaminated hay, which can spread seeds.
  • Remove mud from vehicles and machinery before moving them, as seeds can be carried in mud.
  • 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: Regional priority in 1 of 11 regions. Regional priority weed in North Coast. 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • 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)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources