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Tree-of-heaven (Ailanthus altissima)

Tree-of-heaven forms dense thickets that can restrict movement and outcompete native plants. It can also affect human and animal health, and may taint honey when bees collect pollen from its flowers.

Key facts

Type: Weed, tree.

Native to: North-eastern and central China.

Established in: QLD, NSW, ACT, VIC, TAS, SA, WA.

Other names: Tree of heaven.

Best time to act: Look for the plant when it is in flower in late spring and summer, and treat actively growing plants; do not treat dormant plants in winter with the described basal bark or cut stump methods.

Identification

  • A deciduous tree or shrub that can grow up to 20 m high, often with multiple stems and suckers from shallow roots.
  • Its alternate leaves are usually 20–35 cm long and have 9–21 leaflets, with a single leaflet at the end.
  • Leaflets are dark green, oval with pointed tips, and have toothed or slightly lobed bases with glands that produce an unpleasant odour.
  • Small white or greenish-yellow flowers grow in late spring and summer; separate male and female flowers occur on different plants.
  • Fruits are reddish as they mature, with a single seed in a round disc surrounded by a papery wing.
  • Look-alike: Rhus tree (Toxicodendron succedaneum) has round white to brown fruit up to 1 cm across, and leaflets that turn bright red in autumn.
  • Look-alike: Red cedar (Toona ciliata) has curved leaflets and usually no end leaflet, while pencil cedar (Polyscias murrayi) has leaflets up to 25 cm long and bluish, fleshy fruit about 5 mm long.

Where it grows

In NSW it grows along waterways and gullies, in forests, woodlands, forestry plantations, pastures, urban areas, around abandoned homesteads, and on disturbed roadsides and railway lines.

Why it matters

  • Dense thickets restrict the movement of people and animals and outcompete native plants.
  • The plant is mildly toxic to people if large quantities are ingested; sap can irritate skin and eyes, and pollen can cause allergic reactions.
  • The bark, leaves and flowers are poisonous to animals, and sheep poisoning has been suspected in NSW during droughts.
  • Honey may be tainted if bees collect pollen from its flowers.

How it spreads

  • A mature tree can produce over 300,000 seeds per year; seeds spread most commonly by wind, and also by moving water, ants, birds, machinery, slashers and people dumping garden waste.
  • Shallow lateral roots can produce new trees, especially after the main trunk is cut, and suckers may emerge up to 27 m from the parent tree.

Control options

  • Dig or pull out young seedlings by hand and remove all roots; removing all roots from older plants is difficult once the taproot has developed.
  • For larger plants, use an appropriate herbicide method such as foliar spraying, basal barking, cut stump treatment or stem injection, following the product label and any permit.
  • Check for and manage new suckers from shallow lateral roots, particularly after cutting the main trunk.
  • In the Hunter, notify the local control authority if the plant is found; contact the local council weeds officer for identification advice.

Hygiene and washdown

  • Clean machinery and slashers after working where tree-of-heaven seeds or plant material may be present, as machinery can spread seeds.
  • Do not dump garden waste where it could establish or spread the plant.
  • 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: Regionally controlled / restricted weed (varies by region). Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • 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: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Declared pest, prohibited. It is a declared pest throughout the ACT. Dealing with it, such as selling, moving or keeping it, is prohibited.

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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources