Senegal tea plant (Gymnocoronis spilanthoides)

Also known as: Senegal tea

Senegal tea plant is a highly invasive and destructive aquatic weed occurring in scattered infestations in NSW.

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How does this weed affect you?

Senegal tea plant forms dense stands on the edges of water bodies and also forms mats across the water’s surface that:

• outcompete native plants
• reduce food and habitat for fish and other aquatic animals
• interfere with water flow and ecosystem functions
• restrict recreational activities such as swimming or boating.

What does it look like?

Senegal tea plant grows in dense stands or as clumped bushes up to 2.5 m high. It usually grows at the edges of water bodies or in shallow water, but the stems can extend to form a mat across the surface of deeper waters. Plants are dormant during winter and reshoot the following spring.

Leaves are:

• dark green
• 4–20 cm long and 1.5–8 cm wide
• oval to spear-shaped and tapered to a pointed tip
• irregularly serrated and slightly wavy along the edges
• on short stalks
• in opposite pairs along the stem.

Flowers are:

• white or pale purple
• 1.5–2 cm in diameter
• half-sphere-shaped
• in groups at the ends of the stem
• strongly fragrant
• present from late spring to early autumn.

Seeds are:

• yellow-brown and do not have a pappus
• 0.5 mm long
• ribbed.

Stems are:

• pale green
• 1–1.5 m long and up to 2 cm in diameter
• upright at first then prostrate as they lengthen and age
• branched at nodes and hollow between the nodes
• buoyant, forming tangled floating mats.

Roots are:

• fine and fibrous
• formed at stem nodes.

Similar looking plants

Senegal tea plant looks like:

• Alligator weed (Alternanthera philoxeroides), which has much smaller leaves (up to 7 cm long) and smaller papery flowers (8–10 mm).
• Hygrophila (Hygrophila costata), which has whorled flowers near the stem and leaf junction, and an angular stem.
• Blue water-speedwell (Veronica anagallis-aquatica), which looks similar before flowering but the stems are thinner, only up to 6 mm in diameter. It has spikes of pale blue flowers.

Where is it found?

Senegal tea plant has been found in the North Coast, Hunter, Greater Sydney and South East regions. Many of these infestations have been eradicated.  

Senegal tea plant is native to tropical and subtropical Central and South America. It was introduced to Australia from India for the aquarium trade in the 1970s. Senegal tea plant first appeared as a weed in the Manning River near Taree in 1980.

What type of environment does it grow in?

Senegal tea plant usually grows in tropical, subtropical and warm temperate regions. However, infestations have been found in cold temperate regions of Victoria.

Senegal tea plant prefers still or slow flowing freshwater such as wetlands and along the banks of watercourses and dams. Plants can grow when submerged, but growth is slower, and plants are smaller.

It can also grow in wet areas away from the main water body. Plants have occasionally been found growing up to 150 m from a water body and in gardens.

Maps and records

• Recorded presence of Senegal tea plant during property inspections (Map: Biosecurity Information System - Weeds, 2017-2026)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

By seed

Buried seeds can remain dormant for over 15 years. Seeds need light to germinate, and most new seedlings appear in spring. Some new seedlings appear in summer. Most seeds fall close to the parent plant. The seeds are spread:

• mostly by flowing water
• in mud which sticks to animals, machinery or vehicles
• on boats, trailers and other aquatic recreational equipment

By plant parts

New plants can grow from stem fragments with a node and from leaf fragments if the midrib is present. The stems and leaves are spread by flowing water, animals or by sticking to boats, trailers and other aquatic recreational equipment. They can also be spread by slashers or lawn mowers

References

CRC for Australian Weed Management (2003). Senegal tea plant – Gymnocoronis spilanthoides Weed Management Guide.

Panetta, F. D. (2010). Seed persistence of the invasive aquatic plant, Gymnocoronis spilanthoides (Asteraceae). Australian Journal of Botany, 57(8), 670-674.

Parsons, W.T., & Cuthbertson, E. G. (2001). Noxious weeds of Australia. CSIRO publishing.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 10 December 2024 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Gymnocoronis~spilanthoides

Sainty, G. R., & Jacobs, S. W. (2003). Waterplants in Australia (No. Ed. 4). Sainty and Associates Pty Ltd.

Vivian-Smith, G., Hinchliffe, D., & Weber, J. (2005). Fecundity and germination of the invasive aquatic plant, Senegal tea (Gymnocoronis spilanthoides (D. Don) DC.). Plant Protection Quarterly, 20(4), 145.

More information

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Control

Successful weed control relies on follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.

Prevention

To help prevent the spread of Senegal tea plant when fishing or using waterways for other recreational activities:

• Avoid running motors or paddling through water plants.
• Check your boat/watercraft, trailer and equipment for plant material before you leave a site and before launching at a new site.
• Remember to check the inside of boats, live wells, bilge and bait containers.
• Remove all plant material that you find before you leave a site and before launching at a new site.
• Contact your local council if you think you have seen Senegal tea plant.
• Do not dump plants.
• When buying water plants check that they are not any that are prohibited from sale.

Physical removal

Mechanical and manual removal can be effective in small, accessible infestations. Qualified personnel should treat the Senegal tea plants with herbicide before removing the plant. This reduces the risk of spreading stem fragments.

Disposal

Removed plant material may be dried and incinerated. Contact your local council for advice on other ways to dispose of this weed.

Chemical control

Spot spraying

Apply to all foliage to the point of visible wetness. Do not spray directly onto water. Repeat treatments may be needed.

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2030
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: 200 ml in 10 L of water
Comments: Spot spray application.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the NSW Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
Greater Sydney Central Coast Council area, Royal National Park and the Hawkesbury Nepean River and its tributaries are classified as the core infestation area. An exclusion zone is established for the rest of the region.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: Land managers should mitigate the risk of the plant being introduced to their land. Within exclusion zone: Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation area: Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment.
Hunter	Regional Recommended Measure* (for Regional Priority - Eradication) Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant.
Murray	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
North Coast	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
North West	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Riverina	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Your local biosecurity weeds officer can help to identify, advise on control, and how to remove this weed.
South East	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2024