What does it look like?
Nardoo looks like a member of the clover family, but is actually a freshwater fern. It has flat leaves that resemble a large four-leaf clover. The leaves float on the surface of the water on stalks up to one metre long. The roots form dense, floating masses.
Nardoo grows either as an aquatic or on mud, mostly in areas subject to at least temporary inundation. When the plants are growing in the water they have floating leaflets. Suitable habitats include freshwater that is less than one metre deep, such as swamps, dams, lake edges and garden ponds.
Why is it a problem?
Nardoo can form dense beds of vegetation which can block dams and waterways, impede drainage and disrupt recreational activities. It outcompetes native species, and is also highly toxic to stock.
It is thought that Nardoo does not produce spores in New Zealand and spreads only from plant fragments.