This CSI is Salvinia molesta, or Giant Salvinia, a fast-growing, free-floating aquatic fern that is native to Brazil. Instead of roots, the Salvinia uses a three-leaf or frond approach: two water resistant fronds float atop the surface while the third frond is divided into sections and submersed in the water, serving as a "root."
This giant fern is generally found in fresh water ponds and lakes. The fern forms floating mats up to 2 feet thick that block sunlight and reduce oxygen content to other water-dwelling organisms. The fern's rapid growth rate can completely cover the surface of lakes and streams, and it has the ability to double its surface area in five days. These mats also muck up boating, fishing and swimming.
The Salvinia is hardy and difficult, if not impossible to kill or control once it is established a home for itself. It appears to be resistant to most chemicals, but new biological controls may help correct the problem. A tiny weevil, Cyrtobagous salviniae, is under study as a biocontrol for the invasive Salvinia.
While cool to look at, the Salvinia is viewed as a dangerous pest. U.S. Federal and state laws prohibit the importation, transportation, and cultivation of the Species.
Photo by Scott Bauer. Courtesy USDA.
