Giant Salvinia

Salvinia molesta D.S. Mitchell


Other common names: water fern, Kariba weed.

Identification  |  Biology  |  History  |  Status  |  Range  |  Agents  |  Literature


Giant salvinia has three leaves, two above water and the third submerged. Salvinia forms floating mats that shade and over crowd native plants thus, threatening water quality and the oxygen supply. These mats also form in rivers and irrigation ditches which constrains agriculture. These mats can clog drains, irrigation intakes and be snagged by boats and spread to other areas.


Salvinia molesta is a free floating aquatic fern that grows rapidly to cover the surface of lakes and streams. Giant salvinia can become detrimental to the economy and recreational interests. Giant salvinia reproduces efficiently by the spreading of plant fragments that easily break off when disturbed, and it is not known to reproduce by spores.


Salvinia molesta is an aquatic weed, native to South America, which has recently been found in the Houston area in 1998. It is feared that it may become a major nuisance aquatic weed in Texas.


Giant salvinia has been detected in East Texas, North Texas, Louisiana, Mississippi, Alabama, Georgia, Florida, and Arizona. It is found in certain sites in these states but is not widely distributed. The Federal Noxious Weed Law prohibits the importation of giant salvinia into the United States and the transport across state lines.


Still waters of man-made and natural lakes and ponds, oxbow lakes, ditches, stream margins and wetlands. Expected to occupy habitats favorable to S. minima, yet predicted to extend into and colonize open water more aggressively.

Biological Control Agents


Thomas, P. A., and P. M. Room. 1986. Taxonomy and control of Salvinia molesta. Nature 320: 581-584.  


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