Senegal tea plant

Senegal tea plant (Gymnocoronis spilanthoides) is an aggressive, highly invasive and destructive aquatic weed occurring in scattered infestations in NSW. It is one of 28 weeds on the Australian Government’s National Environmental Alert List. Senegal tea plant is in the early stages of establishment in Australia and could seriously threaten biodiversity if not contained.

Senegal tea plant prefers tropical, subtropical and warm temperate conditions and is a hardy plant with a rapid growth rate in these areas. It will grow in shallow water, damp floodplain conditions, on the margins of creeks and dams (it has been found growing up to 150m from a water body), in wetlands and in still or slow-flowing fresh water. In these situations, Senegal tea plant can form dense, erect stands, or mats, of stems extending from the banks out across the water surface. This can impede water flow, ecosystem function, as well as boating and recreational activities.

World status

Senegal tea plant is native to tropical and subtropical America (from Mexico to Argentina). It is an invasive aquatic weed in New Zealand, India and China.

Senegal tea plant was introduced into Australia from India for the aquarium trade in the 1970s. In 1980 it was recorded as naturalised in the Manning River near Taree. Infestations have occurred at Dapto, Byron Bay and Gloucester. These have since been controlled. Current distribution in NSW includes isolated infestations on the Central Coast and in the Hunter and Sydney regions, including the Royal National Park and the Hawkesbury River. In November 2012 a significant patch of Senegal tea plant was discovered west of Mullumbimby.

Watch out for and report any form of Senegal tea plant.

Identification

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

• Stems are ribbed, pale green and erect, becoming prostrate as they lengthen and age. They are hollow between the nodes and are able to form tangled floating mats. Stems branch at the nodes and are 1–1.5m long and 5–10mm in diameter, increasing to 1–2cm with age.
• The opposite leaves are tapered and dark green, growing from 5–20cm long and 2.5–5cm wide.
• Conspicuous white ball-shaped flowers approximately 1.5cm in diameter with a strong fragrance. Flowering occurs late spring/summer and the seeds are yellow-brown, 5mm in diameter, and ribbed.

Spread

The plant produces roots at the nodes and will propagate new plants from broken pieces of stem or from seed. While Senegal tea plant produces prolific amounts of seed, seed germination appears to be a minor form of spread in Australia. Most new infestations in Australia occur as a result of plant fragments. Plant fragments can be moved in flowing water or flood waters. Plants are dormant during winter, reshooting the following spring from the crown and also from protected buds at nodes on the stems.

Control

Control should not be attempted by individuals as Senegal tea plant can spread very easily from fragments. If you suspect you have found Senegal tea plant, seek advice from your local council weed biosecurity officer to assist with identification, removal and eradication.

If you think you have seen this plant, please contact Rous County Council on 6623 3800.

Distribution map as at May 2017

Predictive mapping supplied by Queensland Biosecurity