Giant salvinia (Salvinia molesta), is an aquatic fern, native to Brazil, but now an invasive weed in many parts of the world.
It grows extremely quickly, capable of regrowing from small fragments and doubling in size every few days, clogging ponds and lakes. Forming mats up to 2 feet thick, the plant gobbles up oxygen and blocks sunlight needed by other water dwellers.
A tiny weevil, Cyrtobagous salviniae[?], is under study as a biocontrol.
External Links
- Wildland Invasive Species Team - Weed alert (http://tncweeds.ucdavis.edu/alert/alrtsalv.html)