Giant salvinia is an invasive aquatic fern in the water-fern family (Salviniaceae). It is native to Argentina and Brazil but is now a global weed. It is a Noxious Aquatic Weed according to the United States Department of Agriculture and the North Carolina Department of Agriculture and Consumer Services. The species epithet is Latin for “bothersome” and refers to the troublesome habit of this plant. The plant grows only in the freshwater of lakes and rivers and can tolerate cold but not frozen water. The mats can be several feet thick and block sunlight and oxygen from getting to the water, to the detriment of fish and native plants. Mats impede boating, fishing, and swimming and clog water intakes for irrigation and electrical generation. Giant salvinia is a free-floating fern with horizontal stems that float just below the surface. A whorl of 3 green leaves (fronds) is produced at each node with a bristly surface caused by the hair-like bristles that join at the end to form eggbeater or whisk shapes. Lower leaves are brown, deeply cut and act as roots. Below those are larger leaves, up to 9 inches, that act as a drag for stabilizing the plant. Sporocarps (spore-producing bodies) develop in elongated chains among the submerged leaves. However, very few spores are formed; this plant reproduces primarily vegetatively. Due to its invasiveness and the harm caused by this plant to natural ecosystems, this fern is not recommended for any garden, aquarium, pond or waterscape. Do not grow this plant. Seek alternatives. Insects, Diseases, and Other Plant Problems: Salvinia weevil, a South American beetle that feeds on the plant, has been introduced into the US as a biological control.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil drainage
Frequent Standing Water
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous
Form & Appearance
Habit / form
Prostrate
Leaf color
Brown/Copper; Green
Leaf type
Fronds
Leaf arrangement
Whorled
Leaf shape
Oblong
Leaf margin
Entire
Leaf size
1-3 inches long, 1-3 inches wide
Hairs present
Yes
Leaf detail
Upper green leaves are in whorls of 3 and are 3/4 to 1.5 inches with hair-like structures that look like small egg beaters for buoyancy. Lower leaves are brown and thread-like acting as roots. The lowest leaves are larger, up to 9 inches, acting as a drag.
Flower detail
No flowers
Fruit detail
Sterile spores are formed in sporocarps
Stem color
Brown/Copper; Green
Stem detail
Branching horizontal stems
Wildlife & Ecology
Native status
Unknown
Origin
Argentina Northeast, Brazil South, Brazil Southeast