Spring sees green shoots appearing along our riverbanks but not all of them are welcome. Some of the plants (or flora) you find along our rivers are "non-native invasive species." These were brought to the United Kingdom from around the world and have spread causing harm to the environment. You can help protect native species and river visitors by learning how to identify and report them.
Himalayan balsam is controlled by pulling plants before they go to seed. It is a popular summer activity with our volunteers.
The seeds are spread by flood water. We focus on controlling it high up catchments to prevent its spread or on sites with high ecological value.
As the first true pair of leaves appears you can see the distinctive serrated edges. It has orchid pink flower.
It is widespread throughout the middle Aire catchment but less so in the Upper Aire.
Japanese knotweed is controlled by injecting stems with pesticide. We treat Japanese knotweed along Bradford Beck. YorGreenCIC treat it in the Bradford area.
Japanese knotweed has heart shaped leaves and a tall stem that looks like a cross between rhubarb and bamboo. It can reach over head height and regrow from fragments of roots.
Identifying giant hogweed seedlings is challenging as they can be confused with native hogweed species.
Giant hogweed looks like an enormous cow parsley. It is significantly larger and can reach heights between 1.5m and 5m with a spread of between 1 and 2m. Leaves are jagged and lobed and a flower spike formed in the second year before setting seed.
Their stems are green with purple blotches and stiff, white hairs. The leaves are huge (up to 1.5m wide and 3m long) and is deeply divided into smaller leaflets. Flowers appear in June and July.
Reporting it through the Yorkshire Wildlife Trust INNS Mapper site is the most effective way to ensure it is treated. In Leeds, this is done by the River Stewardship Company.
Signal crayfish can be found throughout the catchment. There is currently no viable method of control in the United Kingdom.
Large specimens can sometimes be seen from bridges or found under rocks. It is illegal to trap or fish for them without a license from the EA.
Pockets of native white-clawed crayfish populations still remain within the Aire catchment. The best way to protect them is careful biosecurity to prevent the spread of signal crayfish.
How to report them
Both Japanese Knotweed and giant hogweed can be reported through the Yorkshire Wildlife Trust INNS Mapper site is the most effective way to ensure it is treated. You have to create an account to do this. In a future blog we will take you through the process of reporting.