Giant salvinia

Salvinia molesta, commonly known as giant salvinia, is also widely called Kariba weed after it infested a large portion of Lake Kariba between Zimbabwe and Zambia. It is a free-floating aquatic fern, with fronds that are 0.5–4 centimetres (0.20–1.6 in) long and broad, with a bristly, waterproof surface caused by the hair-like strands that join at the end to form eggbeater shapes. The fronds are produced in pairs with a third modified root-like frond that hangs in the water. Though native to south-eastern Brazil, it has been accidentally introduced or escaped to countless lakes throughout the United States, including Caddo Lake in Texas, where the invasive species has caused eutrophication to occur.