Senegal tea is an aggressive freshwater weed that inhabits wetlands and still or flowing waters. Find out how to recognise this plant and check out our tips for control.
On this page: why Senegal tea is a pest, identifying features, how to recognise Senegal tea, responsibility for control, how you can help, further information
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Why senegal tea is a pest
Senegal tea is an aggressive freshwater weed that inhabits wetlands and still or flowing waters. It forms dense floating mats, which can quickly cover waterways or wetland areas, causing a number of serious problems. It has the ability to smother submerged and other native plant species, affecting the health of wetland ecosystems and native biodiversity.
By changing habitats and smothering other useful species, Senegal tea may displace traditional food sources of value to Maori. It may also impede the flow of water, blocking streams and causing flooding, and interfere with recreational activities such as boating.
Senegal tea (Gymnocoronis spilanthoides) is a native of central and southern America (Mexico to Argentina) and was originally brought into New Zealand as an ornamental plant for ponds and aquariums. It was first noted as having naturalised in 1990 in a Papakura Stream. Only a few isolated infestations are known in the Waikato region at present and all have eradication programmes underway.
Senegal tea is spread by seed or stem fragments, which readily form new roots. Seeds can be dispersed by water movement and in soil attached to vehicles, machinery or animals. Fragments can be dispersed by water movement, planting, clearing and dumping pond vegetation or by drainage machinery.
- Oval to tapered dark green leaves 5 to 20 cm long in opposite pairs.
- Serrated leaf margins, slightly wavy.
- Stems are round when young but become six sided as they mature.
- Yellow-brown seed is about 2 mm long, with distinctive ribs.
- Flowers are highly scented and are grouped at the end of stems.
How to recognise senegal tea
Senegal tea is a semi aquatic, sprawling perennial herb. It has dark green leaves with serrated margins, which are arranged in opposite pairs on pale green stems. As stems mature, they become hollow between the nodes (the joints between segments) and float on water. The younger, smaller stems are not hollow.
The stems branch and root at the nodes, forming thick intertwining mats. The flowering stems are erect, growing up to 1.5 metres. Whitish flowers with many florets, resembling 'pom poms', are produced from November to April.
Plants are dormant over winter but grow rapidly over summer, with a growth rate of up to 15 cm per week.
Responsibility for control
Waikato Regional Council is responsible for controlling senegal tea. It is a total control plant under the Regional Pest Management Strategy and we aim to eradicate this plant from the region.
Senegal tea is also banned from sale, distribution or commercial display.
Because it grows easily from fragments, care should be taken not to disturb it or transport it to new sites.
If you think you have seen Senegal tea, please call 0800 BIOSECURITY (0800 246 732) to report it to your local Biosecuirty Plant Pest Contractor.
How you can help
Practice good aquatic pest hygiene by:
- always checking to make sure your boat and trailer are not carrying hitchhiking weeds
- never deliberately releasing any plants to waterways where they are not already living
- never emptying the contents of aquariums into ponds or waterways
- getting to know what plant species are weeds. Report any sightings of Senegal tea or other plant pests to Waikato Regional Council.
Contact your local plant pest contractor for further information and advice.
For enquired on policy and procedural matters call Waikato Regional Council's Freephone 0800 800 401
For more information on plant pests, please visit the Weedbusters website.
- Visit our Waikato Regional Pest Management Strategy
- 'What makes a pest a pest? - A guide to Waikatos pest management future'. Pick up, download or order for free from our offices.
- 'Plant me instead - Plants to use in place of common pest plants'. Pick up or order for free from our offices.
- Download the National Pest Plant Accord.
- 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders'. Pick up or order for $15 from our offices.