Salvinia molesta, commonly known as giant salvinia, or as kariba weed after it infested a large portion of the reservoir of the same name, is an aquatic fern, native to south-eastern Brazil. It is a free floating plant that does not attach to the soil, but instead remains buoyant on the surface of a body of water. The fronds are 0.5–4 cm long and broad, with a bristly surface caused by the hair-like strands that join at... (Wikipedia)