Forms mats on water surface

A free-floating freshwater fern with branching horizontal stems and short feathery ‘roots’ (actually modified leaves), forming mats of foliage on the water surface, native to south-eastern Brazil. Introduced for the aquarium industry it has become a serious problem in rivers, streams, lakes and dams. Plants produce slender, branching runners and form mats of vegetation very quickly. The emerged leaves are oval or two-lobed with water-repellent waxy hairs in rows. The submerged frond is brown and highly divided. The feathery roots and sterile spore sacs are an identifying feature. Declared noxious in all Australian states and territories. Salvinia molesta is a Restricted Invasive Plant in Queensland and Weed of National Significance.

Photo: Sheldon Navie

Photo: Sheldon Navie

This photo shows egg-beater-shaped hairs on leaves. Photo: Sheldon Navie