Senegal tea plant (Gymnocoronis spilanthoides)

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 is a hardy plant with a rapid growth rate, growing on the banks of watercourses and in shallow water. 

Senegal tea can form dense erect stands, or extend mats of stems from the banks across the water surface. This impedes flow, ecosystem function, navigation, and recreational activities. Senegal tea is one of 28 weeds on the Australian Government’s National Environmental Alert List. These weeds are in the early stages of establishment and could seriously threaten biodiversity if not managed.

What does it look like?

Senegal tea is a perennial plant that can grow in dense stands or as clumped bushes up to 1 m high.

Leaves and stems

Stems are ribbed, pale green and erect, becoming prostrate as they lengthen and age. They are hollow between the nodes and buoyant, able to form tangled floating mats. Stems branch at nodes and are 1 – 1.5 m long and 5 – 10 mm in diameter, increasing to 1 – 2 cm with age. Fine, fibrous roots form at stem nodes.

The tapered leaves are dark green, 5 –  20 cm long, 2.5 – 5 cm wide, grow on short stalks and have serrated, slightly wavy margins. They occur in opposite pairs along the stems.

Flowers and seeds

White, pom-pom-like flowers 1.5 – 2 cm in diameter occur in groups at the ends of stems. Flowering starts in late spring or early summer and continues until temperatures fall. Flowers have a strong fragrance. Seeds are yellow-brown, 5 mm in diameter, and ribbed.

Where is it found?

Senegal tea is native to tropical and subtropical America (from Mexico to Argentina). It is an invasive aquatic weed in New Zealand, India and China. It was introduced to Australia from India for the aquarium trade in the 1970s, and was first recorded as naturalised in the Manning River near Taree in 1980. Infestations have also occurred at Dapto, Byron Bay and Gloucester and these have since been controlled. The current distribution in NSW is made up of isolated infestations on the Central Coast, the Hunter and Sydney regions including Royal National Park and the Hawkesbury River.

Maps and records

• Recorded presence of Senegal tea plant during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  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?

Senegal tea reproduces by plant fragments and by seed. Plant fragments develop roots and new stems when they come into contact with soil. Most new infestations in Australia occur as a result of plant fragments. While Senegal tea produces prolific amounts of seed, seed germination appears to be a minor form of spread in Australia. Light is required for seed germination and most seeds germinate in spring (some continue to germinate through summer). Seedlings develop quickly as temperatures increase. Seeds can germinate in shallow water, and most fall close to the parent plant. Seeds can be moved in faster flowing water or in mud on vehicles or animals. Plant fragments can be moved in flowing water or in flood waters. Plants are dormant during winter, reshooting from the crown and from protected buds at stem nodes the following spring.

What type of environment does it grow in?

Senegal tea prefers tropical, subtropical and warm temperate regions, and will grow in damp floodplain soils, on the margins of creeks and dams, in wetlands and in still or slow-flowing fresh water. Plants can grow when fully submerged, but growth is slower and plants are smaller. In some infestations plants have been found growing on the floodplain up to 150 m from the water body.

References

van Oosterhout E (2010). Senegal tea Primefact 993. NSW DPI, Orange. 

Technical reviewers: Rod Ensbey, Melissa Freeman, Birgitte Verbeek.
Information provided by: Kim Hignall and Paul Mason

References

• CRC for Australian Weed Management (2003), Senegal tea plant – Gymnocoronis spilanthoidesWeed Management Guide.
• Hosking J. R, Sainty, G. R., Jacobs, S. and Dellow, J.J., Unpublished Manuscript, "The Australian WEEDbook", Industry & Investment NSW, Orange.
• Sainty G. R. and Jacobs S. W. L. (2003) Waterplants in Australia, 4th Ed, Sainty & Associates Pty Ltd, Potts Point.

More information

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Control

Control should not be attempted by individuals as Senegal tea can spread very easily from plant fragments. If you suspect you have Senegal tea seek advice from your local council weeds officer. This plant can be eradicated if detected early in its establishment.

Physical removal

Mechanical and manual removal can be carried out in small accessible infestations. Issues associated with disposal of the removed plant material and soil and the risk of spreading stem fragments are major concerns. Again it is recommended that control not be attempted by individuals. Qualified personnel should treat infestations with herbicide prior to removing plant material to reduce the risk of spreading viable stem fragments. Removed plant material should be dried and incinerated wherever possible as any plant material and soil that remains damp has the ability to spread viable plant fragments and seeds.

Herbicide options

See Using herbicides for more information.

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PERMIT 14729 Expires 30/06/2024
Metsulfuron-methyl 600 g/kg (Various products)
Rate: 5–10 g per 100 L of water
Comments: Spot spray application. Do not spray directly onto water or non-target species. Senegal Tea Plant can only be sprayed with Metsulfuron Methyl from 1 August to 30 April; repeat treatments may be necessary. Check permit for more critical use comments.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High

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PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: 20mls in 1 Litre 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 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 2023