Salvinia molesta originates from South America
While it was mentioned in the EPPO RS 2009/057 that “S. molesta is considered to be a hybrid between S. biloba and S. herzogii, originating from the botanical garden of Rio de Janeiro”, additional information has been received that contradicts this statement. The plant is incapable of sexual reproduction, but it is though to have hybridized centuries ago, well before the botanical garden of Rio de Janeiro was created (M Julien, pers. comm., 2009). Then, an element which corroborates the fact that the species has not artificially been created, is that Julien et al. (2002) have identified the native range of Salvinia molesta. This area consists of a relatively small area (20,000 km²) in South-Eastern Brazil, including the states of São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. It occurs between the latitudes 24°05’ S and 32°05’ S. Natural enemies which are currently being used as biological control agents were found in this area.
Sources
Julien MH, Center TD ; Tipping PW (2002) Floating fern (Salvinia). In: Van Driesche R, Blossey B, Hoddle M, Lyon S and Reardon R (eds), Biological Control of Invasive Plants in the Eastern United States. USDA Forest Service Publication FHTET-2002-04, 17–32.