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Hairy thornapple (Datura wrightii)

Hairy Thornapple is a scattered naturalised garden escape in Australia, occurring mainly in settled and agricultural areas. All parts are toxic to people and stock, although poisoning records attributed to this species are few.

Key facts

Type: Weed, herb.

Native to: South-western United States and adjacent parts of Mexico.

Established in: NSW, VIC, SA, WA.

Best time to act: Survey during summer and autumn, when it flowers and fruits, and target small plants because mature plants may be less responsive to herbicide.

Identification

  • It is a much-branched, bushy herb that grows to about 1 m high.
  • Its dull greyish-green stems and leaves are covered mainly in backwards-pointing hairs, with some erect, sticky hairs.
  • The leaves are oval, usually 50–100 mm long and 40–60 mm wide, with a few short lobes near the base.
  • Large, white, trumpet-shaped flowers are usually tinged greyish lavender or greyish pink towards the top.
  • The prickly capsules hang or bend downwards and contain numerous yellow-brown to grey-brown, D-shaped seeds.
  • Look-alike: Downy Thornapple (Datura innoxia) is most similar, but has only erect, sticky hairs on its stems and leaves and pure-white flowers; Hairy Thornapple has mainly backwards-pointing hairs and flowers usually tinged greyish lavender or pink.
  • Look-alike: Common Thornapple (Datura stramonium) and Fierce Thornapple (Datura ferox) lack Hairy Thornapple’s velvety hair covering and have erect rather than nodding capsules.

Where it grows

In Australia it occurs as scattered naturalised populations, mainly in settled and agricultural areas south of 31 degrees latitude in South Australia, Victoria and New South Wales, often in fertile, moist soils near habitation.

Why it matters

  • All parts are toxic to stock and people because they contain tropane alkaloids; the roots and seeds are particularly poisonous.
  • There are few reliable records of stock poisoning attributed to Hairy Thornapple and few substantiated records of human poisoning.
  • It is usually sparingly naturalised and is associated with habitation, including derelict gardens and garden-spoil escapes.

How it spreads

  • Seeds can move in water runoff and in transported soil, including mud on vehicles.
  • It can spread as a contaminant of crop seed and through human movement of seed or soil.
  • Dispersal through root fragments also occurs, intentionally or otherwise.

Control options

  • Mechanical removal is feasible for the usually small infestations.
  • Small plants are susceptible to registered herbicides, but herbicide control may be ineffective on mature plants.
  • Take the toxicity of all parts, particularly the roots and seeds, into account when planning control work.
  • No biological control agent is listed.

Hygiene and washdown

  • Check and remove mud from vehicles before moving between sites, as seeds can be carried in mud on vehicles.
  • Avoid transporting soil or crop seed that may contain Hairy Thornapple seeds.
  • 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Declared weed. Weeds Australia lists it as a declared weed in the NT under the Weeds Management Act 2001. Check the NT declared weeds list for its class and what it requires.
  • 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • 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