Giant Salvinia

Appearance

Salvinia molesta, commonly known as giant salvinia or kariba weed after it infested a large portion of the reservoir of the same name, is an aquatic fern, native to south-eastern Brazil.[1] It is a free floating plant that does not attach to the soil, but instead remains buoyant on the surface of a body of water. The fronds are 0.5–4 cm long and broad, with a bristly surface caused by the hair-like strands that join at the end to form eggbeater shapes.[2] They are used to provide a waterproof covering. These fronds are produced in pairs also with a third modified root-like frond that hangs in the water.

Distribution

The Brazilian floating fern known as Salvinia molesta is now widely distributed in tropical and subtropical areas

Habitat

S. molesta prefers to grow in slow-moving waters such as those found in lakes, ponds, billabongs (oxbows), streams, ditches, marshes, and rivers. It prefers nutrient-rich waters such as those found in eutrophic water or those polluted by waste water. It does not usually grow in brackish or salty waters

Reproduction

It reproduces by asexual reproduction only, but it is capable of growing extremely quickly, starting from small fragments and doubling in dry weight every 2.2–2.5 days. It grows from fragments that have broken off or dormant buds that have been detached from the main plant. Each node has five buds so potential for great and rapid spread is high. It also produces spores but they are genetically defective and do not produce viable offspring.

Predators

A tiny weevil, Cyrtobagous salviniae, found in the native habitat of S. molesta, is currently being studied as a biocontrol.