- Small, free floating plant forming dense mats
- Green in spring, turning red/brown in Autumn/Winter
- Up to 2.5cm across
- Dark brown roots
Brought to the UK in the 1880, Water Fern has been dispersed by the wind and is now found across much of the lowlands of the UK.
Water Fern is a floating aquatic plant that can form dense mats on the surface of water. During the summer growing season it can cover whole waterways and be up to 30cm thick.
It is a type of fern, and the leaves form a branch-like structure. The fern-like leaves are up to 2.5cm long. They are normally green in the summer months, though can be tinged red. Unlike duck weed, the leaves clump together in branches and have multiple dark brown roots hanging beneath. They may die back in the winter months, and turn red in colder weather and if the plant is stressed.
Water Fern can be found in still water such as ponds and canals, and can also be found in slow moving rivers.
It has a symbiotic relationship with blue-green algae and can fix its own nitrogen, and as a result can be found in nutrient-poor waters.
As with other invasive aquatics, the dense vegetation shades out other plant species, leading to oxygen depletion and a decline in native wildlife. The dense mats may be dangerous to humans and animals, as they appear solid but there may be deep water underneath.
Large areas of Water Fern can also impact on recreation by impeding access, as well as the aesthetic value of waterways.