Giant Salvinia (Salvinia molesta Mitchell) in Texas: Status and Report

Giant salvinia (Salvinia molesta Mitchell) is an invasive aquatic fern that has been widely distributed around the world for use in aquariums and water gardens. In the wild it forms dense, fast growing, floating surface mats that shade and crowd out native plants. Water quality is degraded and healthy aquatic ecosystems can be destroyed, justifying giant salvinia being labeled the world's worst aquatic weed. Giant salvinia is native to southeastern Brazil and is on the U.S. Federal Noxious Weed List. In April, 1998, the plant was first collected and identified in Texas in the Houston area. Almost three years into the infestation, the spread of giant salvinia shows no sign of abatement in either Texas or the U.S. The plant has now been confirmed, in the wild, in 10 states. In Texas, four public reservoirs including Toledo Bend, Texana, Conroe and Sheldon have serious infestations. Five streams, including the Sabine River below Toledo Bend, are known to be infested. Ten commercial nurseries within the state have eradicated the plant from their property and 27 private lakes/ponds have had confirmed occurrences.