Salvinia

Salvinia is a genus of floating aquatic ferns in the family Salviniaceae. Native to warm regions of the Americas and Africa, several species have become naturalized in other parts of the world. The genus includes species such as Salvinia natans, Salvinia minima, and Salvinia molesta, the latter commonly known as giant salvinia.

Salvinia plants are small, free-floating aquatic ferns that form dense mats on the surface of still or slow-moving water. Leaves are small and rounded and, on the leaf surface, are densely covered with minute hairlike structures that repel water and aid buoyancy. The plant has a shallow root system that anchors the floating frond and helps with nutrient uptake from the surrounding water.

Ecology and impacts: Dense mats shade submerged vegetation, alter gas exchange, and can reduce oxygen levels near the water surface. This can hamper aquatic ecosystems, impede irrigation and drainage, and hinder recreational and commercial activities. Among Salvinia species, S. molesta is particularly notorious as an invasive weed in tropical and subtropical wetlands.

Management: Control measures include mechanical removal, herbicide application, and biological control in some regions. The salvinia weevil Cyrtobagous salviniae has been used to suppress populations of S. molesta in several countries. Early detection and rapid response are important to limit spread.

Taxonomy: The genus is named after Antonio Salvin, and belongs to Salviniaceae, within the order Salviniales of ferns.