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Gaura (Oenothera lindheimeri)

Clock weed is an introduced ornamental that has become naturalised in parts of South Australia, including the Northern Lofty, Southern Lofty and Southern-Eastern regions. It can escape gardens and establish in disturbed areas, where it may compete with other ground-layer plants.

Key facts

Type: Weed, herb.

Native to: South-central United States, including Texas and Louisiana.

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

Other names: White gaura, Butterfly gaura, Lindheimer's beeblossom.

Best time to act: Look for plants when they are flowering in the warmer months, and treat them before fruits mature and release seeds.

Identification

  • It is a perennial herb that grows as a clump, with upright, often branching stems.
  • Its leaves are narrow and lance-shaped, and are arranged alternately along the stems.
  • Loose, elongated sprays of flowers appear at the ends of the stems.
  • Each flower has four petals and prominent stamens; flowers are white or pink and may fade from white to pink.
  • Small, ribbed fruits form after flowering and contain seeds.
  • Look-alike: Other gaura varieties and evening primroses can have similar flowers; clock weed is recognised by its narrow leaves and airy sprays of four-petalled flowers.

Where it grows

In Australia it is recorded as naturalised in South Australia’s Northern Lofty, Southern Lofty and Southern-Eastern regions, and may grow in disturbed sites and around gardens.

Why it matters

  • It can escape cultivation and establish outside gardens.
  • Established clumps may compete with native herbs and grasses for space and resources.
  • Dense patches can change the composition of vegetation in the ground layer.

How it spreads

  • Plants produce seeds that can establish new plants, particularly where soil or ground cover has been disturbed.
  • Seed-bearing garden waste and soil containing seeds can carry the plant to new sites.
  • Incomplete removal may leave the perennial crown or roots able to regrow.

Control options

  • For small patches, pull or dig plants out when the soil is moist, removing the crown and roots; contain seed-bearing material and dispose of it appropriately rather than composting it.
  • For larger patches, use only herbicides registered for the plant and site, following the product label and protecting nearby desirable vegetation.
  • Revisit treated areas for regrowth and new seedlings, and repeat control until the infestation is cleared.
  • For new or spreading infestations, contact the relevant state biosecurity agency or local council for advice on reporting and local requirements.

Hygiene and washdown

  • Clean soil and plant material from vehicles, machinery, boots and tools before leaving an infested site.
  • Do not move seed-bearing garden waste or contaminated soil 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: 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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • 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