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Sagittaria (Sagittaria platyphylla)

An emergent aquatic plant that forms dense stands in irrigation channels, drains and slow rivers, reducing water flow and habitat.

Key facts

Type: Weed, aquatic.

Native to: North America.

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

Other names: Delta arrowhead.

Identification

  • Emergent plant with broad, oval to lance-shaped leaves on long stalks above the water.
  • White flowers with three petals and yellow centres in whorls on upright stems.
  • Spreads by tubers and rhizomes in the mud.

Where it grows

Irrigation channels, drains, wetlands and slow rivers.

Why it matters

  • Reduces channel capacity and water delivery.
  • Displaces native aquatic plants.

How it spreads

  • Seed, tubers and plant fragments carried by water and machinery.

Control options

  • Herbicide control with products permitted near water.
  • Channel drying and excavation in some systems.

Hygiene and washdown

  • Clean excavators and drain cleaning equipment before moving between channels.
  • 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): Weed of National Significance. One of 32 nationally agreed priority weeds, managed through national strategies with all states and territories.
  • Queensland: Restricted matter, category 3. Do not give it away, sell or release it into the environment. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Sale prohibited; Regional priority in 7 of 11 regions. It must not be imported into NSW or sold anywhere in the state. Regional priority weed in Central Tablelands, Central West, Hunter, Murray, North West, Riverina, Western. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Regionally prohibited / regionally controlled weed (varies by region). Where it is regionally prohibited, landowners must take all reasonable steps to eradicate it on their land. Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land.
  • South Australia: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • Western Australia: Declared pest (C3). C3 Management: landholders must manage it to reduce its impact and stop it spreading.
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Declared weed, Class A. Class A: to be eradicated. All declared weeds are also Class C, so they must not be brought into the NT.
  • Australian Capital Territory: Declared pest, notifiable, prohibited. It is a declared pest throughout the ACT. You must report it to ACT Biosecurity. 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
  • 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