Giant Salvinia: Salvinia molesta

Appearance:

Giant salvinia is an aquatic fern prohibited in the United States by Federal law.

Oblong floating leaves, 1/2 to 1 1/2 inches long. Young plants have smaller leaves that lie flat on the water surface. As plants mature and aggregate into mats, leaves are folded and compressed into upright chains. Leaf surfaces have rows of cylindrical hairs topped with four branches that are joined at the tips to form a "cage" (view with hand lens). These hairs give a velvety appearance and repel water. Distinguish from common salvinia, Salvinia minima, which has leaf hairs with branches always free at the tips.

Underwater root-like structures conceal stalks with egg-shaped spore cases attached. Spore cases are not found on young plants.

Habitat:

Currently invading sites in Texas and Louisiana, giant salvinia has the potential to infest aquatic habitats, wetlands and rice fields across the South.  Native to South America, its introduction by humans has caused severe economic and ecological problems in many countries including New Zealand, Australia and South Africa.

Help protect our aquatic resources, watch out for and report giant salvinia.

Giant salvinia may be introduced with aquarium or water garden plants. If you have seen this plant in cultivation or in the wild, please contact the Nonindigenous Aquatic Species Toll Free Hotline:

1-877-STOP-ANS

In Texas, call - Texas Parks and Wildlife Department at 409-384-9965.

In Florida, call - Florida Department of Environmental Protection at 850-488-5631.

Behavior:

Giant salvinia grows rapidly to cover the surface of lakes and streams, spreading aggressively by vegetative fragments. It forms floating mats that shade and crowd out important native plants. Thick mats reduce oxygen content and degrade water quality for fish and other aquatic organisms. Mats impede boating, fishing, and swimming and clog water intakes for irrigation and electrical generation.

Additional Information:

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Giant Salvinia (Salvinia molesta)

Image Credit: R. Helton, Texas Parks and Wildlife Department Design and Production: Texas Sea Grant College Program