Water Lettuce

Water lettuce Pistia stratiottes This is a water plant to be on the alert for in South Gippsland. Local landholders often have there dams invaded by various water weeds causing major problems with water quality and choked pipes and troughs. This plant not common as yet in this district has the potential with our changing climate, warming of farm dams and lack of frosts is set to become a serious weed. It declared noxious in the states to the north and west but not yet in Victoria. It is a free floating perennial aquatic herb, which consists of a dense rosette of overlapping leaves on a short stem with long feathery roots, reproducing vegetatively and by seed. The seeds float and can spread through waterways, and the main colony will also spread by the development of daughter plants. Water lettuce is commonly sold in nurseries and through the aquarium trade. Once established it will spread quickly take over the entire surface of freshwater lakes and dams, rivers and canals. The dense plant mass will reduce light penetration, oxygen concentration and pH levels in the water, thus destroying the habitat of fish and is a good shelter for mosquitoes. Control is difficult mainly by manual of mechanical removal. Chemical control is possible but not desirable.