salvinia infestation




pronounced: sal-vin-ee-AY-see-eye

the salvinia family

Both the family and the type genus Salvinia are named for Anton Maria Salvinia (1653–1729), an Italian naturalist and classicist. These are floating herbs, often forming a dense mat over still waters. The plants are small, with creeping branched stems bearing hairs but no true roots. The leaves occur in whorls of 3, two of them green, either sessile or with short petioles, flat, entire, and floating; the remaining leaf is finely dissected, petiolate, root-like, and pendant. The submerged leaves bear sori that are surrounded by basifixed membranous indusia. The only other genus in the family is Azolla, which changes its colour from green to red when exposed to the sun, and its presence in waterways is not usually so harmful: indeed, it has some benefits. It provides habitat and food for small organisms, and can discourage discourage blue-green algal blooms by restricting the penetration of sunlight. Its presence can also restrict the growth of such plants as Salvinia. It does not usually have a seriously negative impact unless it reaches almost total coverage of the water surface


Photograph © Donald Simpson, taken at Horseshoe Bay lagoon 2010