A native of South America, its introduction in Australia, New Zealand, and South Africa has caused severe economic and environmental problems. Giant salvinia spreads rapidly producing dense surface mats in lakes and streams. These floating giant salvinia mats shade out native vegetation and reduce oxygen concentrations. They also accelerate the aging processes in waterbodies and destroy their ability to provide habitat for native invertebrates and fish. Giant salvinia infestations can also impede recreational boating, fishing, and swimming activities, and clog water intakes used for irrigation and power plant generation causing severe economic hardship.
Young plants have smaller leaves that lie flat on the water surface.
Spore cases are not found on young plants. These hairs give a velvety appearance and repel water. Boaters and anglers can help prevent spread by removing all aquatic plants from propellers, intakes, trailers, and gear before leaving a launch area. Always blow out jet ski intakes and wash boats and equipment land-side before traveling to a new waterway. Giant salvinia may be introduced with aquarium or water garden plants.