Giant Salvinia

(Salvinia molesta)

Keys to Identification

Giant salvinia is an aquatic fern that floats on the surface of the water in ponds, lakes, and slow moving creeks. It reproduces by spores.
It is not known to occur in Colorado at this time but it has been spotted in the past. It is thought that this plant was an accidental introduction to the US through the aquarium trade. It is important to not spread it so cleaning boats and other equipment is an important method of prevention.

Family: Salviniaceae (True Ferns)

Other Names: Kariba weed, African pyle, aquarium watermoss, koi kandy

USDA Code: SAMO5

Legal Status: Colorado Noxious Weed List A

Identification

Lifecycle: Perennial or annual

Growth form: Floating fern, herbaceous forb.

Flower: N/A

Seeds/Fruit: Spores produced in long chains of sporocarps found on the submerged leaves.

Leaves: Upper leaves green with white bristly hairs that are split and resemble eggbeaters. Submerged leaf brown, finely divided.

Stems: Horizontal stems float just below the water's surface.

Roots: Rootless

Seedling: N/A

Similar Species

Exotics: Salvinia auriculata, S. biloba, S. herzogii

Natives: none

Impacts

Agricultural: Clogs lakes, ponds, streams, irrigation ditches

Ecological: Forms a dense mat that shades the water. Changes the oxygen content of the water both by preventing surface exchange and decomposing material which accumulates on the bottom surface of the waterbody.

Habitat and Distribution

General requirements: Freshwater lakes, ponds, slow moving streams and rivers. Biomass can double in 7-10 days.

Distribution: Not presently known to occur in Colorado. Found in southern US states

Historical: Native to South America

Biology/ Ecology

Life cycle: Perennial or annual

Mode of reproduction: Vegetative fragmentation spores

Dispersal: Water movement, animals, man, and equipment

Integrated Management Summary

Freezing. Can survive periods of stress. Herbicides.

References

Jacono, C.C. The Biology of Salvinia sp., Internet: 7/29/04, Available:http://www.ceris.purdue.edu/napis/pests/gs/facts/bio.html

Jacono, C.C., USGS, Internet: 2/25/03 Available: http://salvinia.er.usgs.gov/html/identification.html

CWMA