Gymnocoronis spilanthoides (ASTERACEAE) Senegal Tea

Weeds to Whack

Senegal Tea is a highly invasive aquatic weed. It is listed as a Class 1 weed under State legislation and is included on the Federal alert list for environmental weeds – non-native plants that threaten biodiversity and cause other environmental damage. Senegal Tea can quickly take over slow-moving waterways and wetlands, where it forms clumps up to 1 m tall. It has been located in Ithaca Creek on several occasions and has been treated. Vigilance is required to continue to monitor and treat current infestations.

Photo: Sheldon Navie

Foliage

Senegal Tea is a fast-spreading plant that reproduces through both seed production and vegetatively through stem fragmentation at the nodes. It is a broad-leaf emergent which can be identified by its glossy, dark green leaves which are opposite and spear shaped with serrate margins. The stems are hollow which gives the plant added buoyancy and are a good identification feature. If you find Senegal Tea, report it immediately to your local council. Class 1 pest plants are serious weeds, but are not generally established in Queensland, thus there is a need to eradicate them quickly when they are found.

Photo: Sheldon Navie

Flowers

The numerous, 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 (Pier 2005). Gymnocoronis spilanthoides is a freshwater or marsh-growing emergent perennial herb. It has been introduced through the aquarium trade. It grows very quickly and can rapidly cover water bodies with a floating mat that excludes many animals and plants from native vegetation. Localized flooding increases because G. spilanthoides blocks drainage channels. Recreational activities, irrigation and navigation may also be affected. And if large-scale die-offs of this species occur, water quality may decline. Global Invasive Species Database on Senegal Tea

Photo: Sheldon Navie