Family: Salviniaceae (Water Fern Family)
Duration and Habit: Annual, Perennial Fern
Salvinia is a rootless, aquatic fern. Emergent groups of leaves (fronds), oblong and flat or semi-cupped, grow in chains and float on the water surface forming dense mats. Leaves grow in pairs and are approximately 1/2 inches wide and 1 inch long. A brown, thread-like leaf hangs underwater; all join at a node along a horizontal, underwater stem. The upper surface of the green leaves is covered with rows of white, coarse hairs, acting as a water repellent. The hairs of giant salvinia are joined at the tips in an egg beater shape.
Ecological Threat: Dense mats of salvinia shade out native aquatic species and reduce dissolved oxygen levels in the water. Agricultural water use is impacted as salvinia obstructs intake pipes for irrigation. Recreational fishing and boating may be hindered by dense mats.
Biology & Spread: While Salvinia may reproduce via spores as other ferns do, U.S. populations more commonly reproduce via budding from both attached nodes or broken stems. As many as five lateral buds can be found at one node. Populations can double every 2 weeks in the wild, and small quarter-acre ponds have been completely covered with giant salvinia in as little as 6 weeks from the point of invasion.
History: Giant salvinia is a popular aquarium plant. It was first detected outside of aquarium and landscape cultivation in South Carolina in 1995, was found in Texas in 1997, and rapidly spread to other southern states over the following years.
U.S. Habitat: Salvinia thrives in slightly acidic, high nutrient, warm, slow-moving freshwater. Found in streams, lakes, ponds, ditches, and even rice fields. Resistant to periods of low temperature, dewatering, and elevated pH levels. Low tolerance to salinity.
U.S. Nativity: Introduced to U.S.
Native Origin: Brazil
U.S. Present: Texas, Louisiana, Mississippi, Alabama, South Carolina, North Carolina, Georgia, Florida, Arizona, California, Virginia, and Hawaii.
Distribution: Giant salvinia has been reported from Virginia to California as well as Hawaii, but the majority of infestations currently exist in Texas and Louisiana. Locally it is found in water bodies in Friendswood, League City, Alvin, Houston, Channelview, Mont Belvieu as well as in the Sheldon Lake State Park and Trinity River National Wildlife Refuge. Common salvinia occurs from South Carolina to East and Central Texas. No known populations in the Houston-Galveston region.
If you believe you have found giant salvinia, please report this species.
List All Observations of Salvinia molesta reported by Citizen Scientists
American lotus (Nelumbo lutea), White water lily (Nymphaea odorata), Floating heart (Nymphoides aquatica).
The best control is to prevent further infestations. Enclose harvested biomass and dispose in upland areas away from water. Herbicides (copper carbonate or Rodeo) are necessary for large populations. Biocontrol (Salvinia weevil) may also be effective.USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.
The Quiet Invasion: A Guide to Invasive Plants of the Galveston Bay Area. Lisa Gonzalez and Jeff DallaRosa. Houston Advanced Research Center, 2006.
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