Pest plant - Water hyacinth

Water hyacinth (Eichhornia crassipes) is a perennial floating weed that forms dense mats, reducing water quality and impeding water flow.

Description

erect plant, to 600mm
dark green rounded leaves to 300mm in diameter held upright by swollen stems
leaf stalk is thick and spongy, with bladder-like swellings
bluish-purple or lilac-coloured flowers, 50-80mm in diameter with a yellow centre carried in dense spikes projecting to 600mm above the plant.

blocks sunlight and air exchange from the water
can cause up to four times the loss of water from normal water surface evaporation due to high rates of transpiration through the leaves
rotting plants remove oxygen from the water causing pollution, stagnation and death of fish, crustaceans and other aquatic organisms
large mats create breeding sites for mosquitoes
large infestations can restrict water flow in irrigation channels and interfere with irrigation equipment
reduces the amenity value of aquatic areas by preventing swimming and boating.

reproduces by seed and above ground shoots, most common in lagoons and pools
flowering occurs from October throughout the summer months
flower remains open for several days before withering and releasing seeds into the water after 18 days.