This is a robust, erect, clump-forming perennial aquatic weed that is attached to the waterway floor. It can grow up to 1 metre high and its stem has a milky sap.
Leaves are pale green, velvety and up to 28 centimetres long and 20 centimetres wide with parallel veins. The leaf blade is narrow when young and becomes more oval with age. They are arranged opposite each other on the stem.
Flowers during spring and summer and has up to 15 yellow, cup shaped flowers on long triangular stalks arising in the leaf axils.
Seed capsules produced after flowering split into 12 to18 crescent shaped pieces which contain numerous brown seeds.
Habitat it is found growing in saturated, fertile and muddy conditions.
Weed characteristics it can invade wetlands, rivers and dams. It can restrict water flow and become a silt trap. It is a good breeding area for mosquitoes.
Dispersal it reproduces from cuttings, detached leaves and stems, and by the numerous seeds. Seeds are spread by water, birds and animals and by mud sticking to vehicles, machinery and foot wear.
This species is a Class 1 declared plant under Queensland legislation.
How to act
New infestations must be reported to Biosecurity Queensland on 13 25 23. The plant must be identified and removed by approved officers and have their locations recorded prior to removal. There are no herbicides currently registered for use specifically for this plant. Hand removal of individual plants or small infestations is recommended.
Refer to Weed Control Methods.
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