Home Plants Control Options Ecology ID Systems
Plant Info Overview
Plant List
       Total List
       By Plant Type
Plant ID Systems
       Expert ID Sys
       Continue Expert ID Sys
       Free Selection ID Sys
Glossary

Last Updated: Spring 2012
Click to view plant video.


Synonyms: NONE

Family: Salviniaceae

Home Range/U.S. Introduction:
Salvinia molesta is native to southeastern Brazil. Introduction of the mat forming fern is thought to have arisen from the water gardening and/or aquarium trade where plants are either sold directly or occur as contaminants in water garden stock. Infestations have been reported from several states including Texas, Alabama, Mississippi, Louisiana, Florida, and Hawaii. The predicted range of the plant in the U.S. approximates the current distribution of waterhyacinth.

U.S. Range Map:



Distribution was determined by a combining of the distribution information obtained from the following websites:

USDA, NRCS. 2012. The PLANTS Database (http://plants.usda.gov, 18 June 2012). National Plant Data Team, Greensboro, NC 27401-4901 USA.

U.S. Geological Survey. [2012]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/18/2012].


Species Description:
Giant salvinia is a free floating aquatic fern. An individual plantlet consists of a horizontal stem that produces two floating leaves (fronds) up to 25 cm long and a highly dissected submerged frond up to 25 cm. The floating leaves are green, sessile to short petiolate, broadly ovate in shape with entire margins. The midrib extends from the base to the apex of the leaf. The upper surface of the floating fronds is covered with parallel rows of hairs that have a characteristic "cagelike" structure at the apex. When plants are young, these leaves are small and float on the water surface. As plants age, the floating leaves become crowded and fold against one another resulting in a more vertical leaf position. The brown, feathery submerged leaf resembles and functions as a root. This frond bears the sporocarps or spore forming structures. The globose sporocarps are densely hairy, short stalked and 2-3 mm in diameter. Spores are rarely formed and if present are deformed and infertile.

Habitat/Growth Characteristics:
Giant salvinia grows best in stagnant or slow flowing water. Quiet waters of lakes, ponds, bays, oxbows, ditches, swamps, and marshes may be susceptible to invasion. In Ceylon, the species has proven to be problematic in rice fields. The rhizomatous plant can rapidly form dense floating mats of vegetation. Disturbance usually results in fragmentation and any fragment having an axillary bud can give rise to a new plant. The optimum temperature range for growth is 25-28 deg C and under these conditions plants can double within 1 week.

Problems:
Giant salvinia can impact irrigation systems, navigable waters, fisheries, electric power production, and rice farming. Giant mats reduce light penetration and result in oxygen depletion. As light becomes limiting, it affects the growth and survival of phytoplankton and vascular plants. Oxygen depletion may be so severely reduced beneath a mat that it influences fish survival. Extensive mats may exacerbate a situation because they prevent water circulation and mixing.