Mexican Water Lily
The Mexican Water Lily was introduced from Mexico and south east America. The Mexican Water Lily (Nymphaea mexicana) is an introduced perennial lily which has dark green leaves with a reddish tinge, often blotched with brown. The underside of the leaf has distinct, fleshy venations. Its leaves have a wavy margin, are often concave and are usually crowded and overlap. The flowers are bright yellow and emerge above the surface of the water. The plant has vertical knobbly rhizomes which take root in the substrate and produce new horizontal stems (stolons). If these stolons break, they can re-establish elsewhere. Once established this plant can be difficult to eradicate (Sainty and Jacobs, 2003). The species is a non-declared environmental weed.
Sainty G.R. and. Jacobs S.W.L., 2003. Waterplants in Australia. Sainty and Associates Pty Ltd, Australia.
Case Study - Robina Lakes
In the past, Council has harvested some of the exotic lilies inhabiting the lakes. Where appropriate, native lilies, for example Snowflake Lily (Nymphoides indica), are left in the lakes. These lilies provide food and habitat for aquatic organisms and help to maintain water quality. Some exotic species, such as the Mexican Water Lily, can have a negative effect on aquatic environments and water quality, particularly if growth is left unchecked and they outcompete native species, dominating the environment.
Experience shows that harvesting the Mexican Water Lily is an unsustainable approach to managing this species. Residents and Council officers have observed rapid and thick re-growth of this lily in some patches in Robina South Lake shortly after harvest.
Council has implemented an integrated management program for the control of Mexican Water Lily in Robina South and West Lakes. Initially, all instances of this invasive lily were mapped. Foliar application of registered herbicides was subsequently undertaken. Decaying plants were then mechanically removed as part of the aquatic vegetation harvesting program. A monitoring program was implemented to ensure there were no detrimental effects to the environment, due to off-target damage or water quality impacts from decomposing plant material.
Council's Pest Management unit will manage the application of herbicide on selected patches in Clear Island Waters and Robina South and West Lakes. Officers are highly trained in the use of herbicides and will be using a product registered for use in aquatic environments.
For more information, contact Council's Pest Management unit on (07) 5581 7914.