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Senegal tea plant (Gymnocoronis spilanthoides)

Senegal Tea Plant is a highly invasive aquatic weed found in scattered infestations around Australia. It can block drainage channels and degrade wetlands by displacing native plants and animals.

Key facts

Type: Weed, aquatic.

Native to: Tropical and subtropical regions of the Americas, from Mexico to Argentina..

Established in: QLD, NSW, VIC.

Other names: Temple Plant, Senegal Tea, Spade Leaf Plant.

Identification

  • It may grow as an erect, rounded bush up to 1 m tall, or scramble from waterway edges and form dense mats in open water.
  • Its dark green, spearhead-shaped leaves are 50–200 mm long, arranged in opposite pairs, and have serrated edges.
  • Stems are hollow between the nodes as they mature, can reach 1.5 m long, and may float on water.
  • White or purplish-white ball-shaped flower heads, 15–20 mm across, grow at stem ends.
  • Look-alike: Hygrophila has non-hollow stems, leaves with entire margins, and smaller white flowers about 10 mm across in the leaf forks.
  • Look-alike: Siam Weed, Crofton Weed and Mistflower are terrestrial plants with non-hollow stems and smaller flower heads than Senegal Tea Plant.

Where it grows

In Australia it occurs in wetlands, particularly degraded waterways, and can grow in still or slow-moving fresh water and on wet marshy soils near water.

Why it matters

  • It can quickly take over wetlands, reducing their environmental value, natural beauty and recreational potential.
  • It blocks streams and drainage channels, and has caused flooding in New Zealand.
  • Even tiny pieces of vegetation can form new colonies, making the plant difficult to control.
  • Herbicides used in water may pose a risk to non-target plants and animals.

How it spreads

  • Stem fragments containing a node can break away, root when they settle, and grow into new plants; detached leaves can also reproduce from their veins.
  • Fragments may be moved accidentally on boats, trailers or lawnmowers, or in animals’ hooves.
  • Seeds contribute to local and long-distance dispersal, and plant swapping or trading by butterfly enthusiasts is a likely pathway for secondary invasions in Australia.

Control options

  • Report new outbreaks promptly to your state or territory weed management agency or local council, and do not attempt control without their expert assistance.
  • Poorly performed or incomplete control can help spread the weed and worsen the problem.
  • Hand pulling may cause regrowth and further spread, though it can be effective for small infestations.
  • Professional mechanical control may combine herbicide treatment with removal of silt and plant material; seek agency advice on approved methods and registered herbicides.

Hygiene and washdown

  • Check boats, trailers, machinery and lawnmowers for plant fragments before moving them between waterways, as fragments can spread the weed.
  • 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): National Environmental Alert List. One of 28 weeds named on the National Environmental Alert List as early-stage invaders with serious potential to harm the environment.
  • 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: Regional priority in 7 of 11 regions. Regional priority weed in Greater Sydney, Hunter, Murray, North Coast, North West, Riverina, South East. 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: 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 (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • 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, 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

Sources