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Salvinia molesta
Also called Giant Salvinia, African Pyle, African Payal, Salvinia, Salvinia Moss, Aquarium Watermoss, Water Fern
Kariba-weed (Salvinia molesta) is a free-floating aquatic fern from southeastern Brazil that has become a serious invasive pest in many warm regions. It is grown mainly as an aquarium or pond plant, and it spreads so fast that it is not suited to open waters.
Salvinia molesta, commonly known as giant salvinia, is a free-floating aquatic fern native to southeastern Brazil. It is invasive in many parts of the world, especially southern Africa, where it is commonly known as Kariba weed due to its infestation of Lake Kariba, a large artificial lake situated between Zambia and Zimbabwe. The fern is notable for its long and broad fronds and bristly, waterproof surfaces. The fronds are produced in pairs, with a third modified root-like frond that hangs in the water.
S. molesta has been accidentally introduced to several lakes throughout the world. Since 2019, it has been included in the European Union's list of invasive alien species of Union concern. The species cannot be legally imported, cultivated, transported, commercialized, planted, or intentionally released into the environment in the European Union.
S. molesta reproduces by asexual reproduction. It is capable of growing extremely quickly, starting from small fragments and doubling in dry weight every 2.2–2.5 days. The fern can grow from fragments or dormant buds that have been detached from the main plant. Each node can produce up to five buds, allowing the plant to spread rapidly under favorable conditions. The plant also generates genetically defective spores that do not produce viable offspring.
S. molesta prefers to grow in areas of slow-moving water, such as those found in lakes, ponds, oxbow lakes, streams, ditches, marshes, and rivers. It prefers nutrient-rich waters, and thrives in bodies of water that are eutrophic or polluted by wastewater. The fern usually does not grow in brackish or salty water, but its presence has been reported in streams with a tidal flow in southeast Texas. It can tolerate dewatering, as well as exposure to low or very high temperatures, although it prefers to grow in moderate temperatures.
S. molesta is native to Brazil, but is now widely distributed in global tropical and subtropical climate zones. It is known for taking over large bodies of slow-moving fresh water. S. molesta has been naturalized in Texas and Louisiana, and has also been observed and reported in Alabama, Mississippi, Florida, and Georgia. It can also be found where the lower Colorado River borders Arizona and California. The regions of Texas where S. molesta is naturalized contain a total of 14 drainage basins with infested water bodies; these basins are used as impoundments on tributaries that flow near federally protected wetlands. In October 2020, the Texas Parks and Wildlife Department detected specimens of S. molesta in the Lone Star Lake within the city of Marshall while surveying fish populations.
Text excerpted from the Wikipedia article Salvinia molesta by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
