Invasive Non-native Plants within Wiltshire

Invasive non-native plants are plants that have not evolved naturally in the UK and cause problems for our native wildlife, our health and our economy. Invasive non-natives are a small fraction of non-native plants in Britain, which all evolved outside of the UK and are now found throughout the UK, but generally exist in a benign state in our ecosystems.

The presence of non-native invasive plants in Wiltshire poses a significant threat to the characteristic species and habitats of Wiltshire. Many of the plant species have entered this country through the horticulture trade and have spread due to escape and incorrect disposal of plant material.

These species can:

• Out-compete and displace the native flora and fauna (plants and animals) found in Wiltshire.
• Contribute to the erosion of river banks, causing bank instability and an increase in the likelihood of flooding.
• Cause a significant threat to human health, particularly Giant Hogweed whose sap can cause painful blistering.
• Hinder access to the river banks for landowners, walkers and anglers.
• Cause structural damage, especially Japanese Knotweed which has been known to grow through asphalt and other surfaces.

Unfortunately the risks associated with these invasive species are unlikely to disappear. Climate change may exacerbate the problem as new non-native species are able to survive and flourish in Britain.  

Three most invasive invasive non-native plant species currently causing a threat in Wiltshire include Japanese Knotweed (Fallopia japonica), Giant Hogweed (Heracleum mantegazzianum) and Himalayan Balsam (Impatiens glandulifera) Others to be aware of include Parrot’s Feather (Myriophyllum aquaticum), Water Fern (Azolla filiculoides), Floating Pennywort (Hydrocotyle ranunculoides), Creeping Water-primrose (Ludwigia peploides) and New Zealand Pygmyweed (Crassula helmsii).

How You Can Help

We need any sightings of invasive plants within Wiltshire to be reported. Submit your sightings on via our on-line recording form; they will then be used to assess the scale of the problem of invasive non-native plants in Wiltshire. Alternatively download a paper recording form to print out and return to us with your records.

Find Out More

The Wessex Chalk Streams project initiated the Wiltshire Wildlife Trust's involvement in eradicating non-native invasive plants on the Salisbury Avon river catchment in 2006 through Heritage Lottery Funding through the Living River Project. Since then the Project has concentrated on raising awareness of the problem with the general public and with land managers; producing numerous press releases, leaflets, posters and giving talks. 

The Wiltshire Invasive Plants Project (WIPP) is a three-year initiative funded by SITA Trust and Natural England. The project aims to tackle invasive plants in Wiltshire and Swindon by targeting three species; Giant Hogweed, Japanese Knotweed and Himalayan Balsam. It aims to identify where these species are growing and offer landowners assistance with advice, information and volunteer pulling tasks for Himalayan Balsam. The project also aims to collate and map records on the distribution of invasive plant species throughout Wiltshire, in order to contribute to the wider records for the UK and allow us to assess the scale of the problem.