Description
Senegal Tea Plant (Gymnocoronis spilanthoides) can grow as an erect, rounded bush up to 1 m tall, but is more commonly found as a scrambling form extending from the edges of waterways, and forming dense tangled mats in open water. Young stems are 5-10 mm in diameter, increasing to 20 mm with age. Larger stems are hollow between the nodes (the joints between segments of stem) and float on water, and can reach a length of 1.5 m. The leaves are dark green, 50-200 mm long and arranged in opposite pairs along the stem. The edges of the spearhead-shaped leaves are serrated. The numerous, white or purplish-white, ball-shaped flowers, 15-20 mm in diameter, occur at the ends of stems. The ribbed seeds are yellow-brown and 5 mm in diameter. Thin, fibrous roots can develop at any node that is in contact with moist soil or immersed in water.
For further information and assistance with identification of Senegal Tea Plant contact the herbarium in your state or territory.
Distribution:
The first naturalised specimen is believed to have been collected in 1980 from Oxley Island in the Manning River near Taree, New South Wales. Additional infestations are known to exist at four locations from Taree in the north to Dapto in the south of New South Wales. An infestation has also been discovered in Tasmania, and recently from Perth and South Cranbourne in Victoria.
Queensland recorded the first naturalised plants in 1995 at Redland Bay and since then small infestations have been found near Brisbane and in Cedar Creek at Mt Tamborine.
Habit:
Aquatic
Key points:
- Senegal Tea Plant (Gymnocoronis spilanthoides) is a highly invasive aquatic weed occurring in scattered infestations around the country.
- It blocks drainage channels and degrades natural wetlands by displacing native plants and animals.
- Preventing its further introduction and spread will require greater public awareness of how to identify it and the risks that it poses.
- Contact your state or territory weed management agency or local council if you find Senegal Tea Plant. Do not attempt control on your own, as it can spread very easily from dislodged fragments.
How it spreads:
Vegetative spread occurs when any part of the stem that includes a node breaks away from the main plant, e.g, in fast flowing water. When the stem fragment settles on the stream bed it sends out fine roots from the node, and can grow into an entire new plant. Detached leaves also have the ability to reproduce from leaf veins. Stem fragments can also be accidentally spread by transport of machinery, e.g, boats, trailers, lawnmowers or in animals’ hooves Seeds are also responsible for local and long distance dispersal. Butterfly enthusiasts are known to favour this plant due to its fragrant flowers, so it is attractive to butterflies. Plant swapping and trading between butterfly enthusiasts is a likely pathway for secondary invasions within Australia.
Recent research has shown that seed production in infestations near Brisbane are extremely low, less then 1% of its potential, which indicates that spread of Senegal Tea Plant by seed is not very important there.
Where it grows:
Senegal Tea Plant grows in wetlands, particularly degraded waterways. It can flourish in still or slow-moving fresh water, rooted in the bank and floating out into the waterway. It survives and continues growing even when completely inundated. It also grows on wet marshy soils near water. Senegal Tea Plant grows very quickly in fertile environments, with growth rates exceeding 150 mm a week.
Flower colour:
White
Distribution map:
Impacts:
Senegal Tea Plant is on the Alert List for Environmental Weeds, a list of 28 non native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia’s ecosystem.
Senegal Tea Plant poses a significant risk to the health of wetland ecosystems. It can quickly take over wetlands and detract from their environmental value, natural beauty and recreational potential. In New Zealand it has caused flooding by blocking streams and drainage channels. It could potentially infest wetlands throughout much of Australia. It has a wide climate tolerance and has been found in cultivation well outside its predicted range. It is also very difficult to control because it can spread by both seed and vegetative reproduction, with even tiny pieces of vegetation giving rise to new colonies. Because it is found mainly in water, the potential impact of herbicides on nontarget plants and animals is a potential risk.
Origin:
Senegal Tea Plant is a native of tropical and subtropical regions of the Americas, from Mexico to Argentina, where it has also been recorded as a weed. New Zealand and India are other countries where it has become weedy.
History:
Senegal Tea Plant was introduced to Australia by the aquarium trade, possibly in 1974. It is mainly spread by the careless disposal of aquarium plants or deliberate cultivation for sale.
