The common salvinia is a free-floating fern from South and Central America.
It is a tiny plant made up of just a few small leaves that are covered with stiff leaf hairs. A small tuft of root-like hairs hang in the water and absorbs nutrients.
Common salvinia can multiply quickly and clog waterways as well as shade out native species of plants. It is pushed by the wind or current and can come and go in a particular area.