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.

Photo: Sheldon Navie

Feathery roots and sterile spore sacs

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.

Photo: Sheldon Navie

Egg-beater-shaped hairs on leaves

This photo (thanks to Sheldon Navie) shows egg-beater-shaped hairs on leaves.

Declared noxious in all Australian states and territories. Other Salvinia spp (not molesta) are Class 1 in Queensland.

Photo: Sheldon Navie