Salvinia molesta Mitchell (Giant salvinia )

 


Keith Bradley,
Botanist/Conservation Biologist, Bugwood.org

 

 

 

Family: Salviniaceae (Water Fern Family)

Synonym(s):

Duration: Annual, Perennial

Habit: Fern


Listed by:
Invasive Plant Atlas of the US: 1
Federal Noxious Weed: 1
TDA Noxious Weed: 1
TPWD Prohibited Exotic Species: 1

Description: Salvinia is a rootless, floating aquatic fern. Emergent groups of leaves (fronds), oblong and flat (smaller growth forms) or semi-cupped/folded (larger growth forms), grow in chains and float on the water surface forming dense mats. Leaves grow in pairs and grow to approximately 1/2 inches wide and 1 inch long. Brown, thread-like leaves hang underwater, joining at a node along a horizontal, underwater stem and are similar in appearance to a root system. 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.

If you believe you have found giant salvinia in Texas, please report it here.

History: Giant salvinia is a popular aquarium and water garden 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 within Texas as well as to other southern states over the following years.

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. Salvinia is easily spread by hitchhiking on boats and locally by birds and aquatic mammals and can also spread within water bodies and basins by wind, currents, and flooding.

Ecological Threat: Dense mats of salvinia shade out native aquatic species and decaying leaves can reduce dissolved oxygen levels in the water. Agricultural water use is impacted as salvinia obstructs intake pipes for irrigation. Recreational fishing, boating, and duck hunting are often significantly hindered by dense mats.

US 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. This invasive plant has low tolerance to salinity and does not tolerate brackish waters.

Distribution

US Nativity: Introduced to U.S.

Native Origin: Brazil

US States: AL, AZ, AR, CA, DC, FL, GA, HI, LA, MS, MO, NC, PR, SC, TX, VI, VA.

Resembles/Alternatives: Native Texas alternatives include

Management: The best control is to prevent further infestations. Physical removal of giant salvinia can be effective in small areas such as boat slips but treatments with herbicides are necessary to control extensive infestations. Because giant salvinia is prohibited in Texas, a permit may be required for physical removal. Biocontrol using Salvinia weevils (Cyrtobagous salviniae) may also be effective although these weevils are not currently available to the public because production is limited and permits cannot be issued for possession and transport of the giant salvinia containing the weevils. A nuisance aquatic vegetation treatment proposal is required for chemical, physical, or biological control of any aquatic plant species on a public water body

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.

Listing Source

Texas Department ofAgriculture Noxious Plant List
Texas Parks and Wildlife Department Prohibited Exotic Species
Invaders Program
Federal Noxious Weed
Union of Concerned Scientists
United States Forest Service Southern Research Station

Text References

The Quiet Invasion: A Guide to Invasive Plants of the Galveston Bay Area. Lisa Gonzalez and Jeff DallaRosa. Houston Advanced Research Center, 2006.

Data Source


Giant Salvinia News Roundup, Texas Parks & Wildlife.
Giant Salvinia in Texas Invasive Plant Database.

Last Updated: 2019-08-30 by Monica McGarrity, TPWD; original: LBJWFC