Invasive Species

When carrying out an environmental legal audit at a company, the most common answer to the question ‘Do you have any invasive species on site?’ is ‘What’s an invasive species?’

In this blog I will provide information and pictures on invasive species, and explain why companies have legal requirements if they (and injurious weeds) are found on site.

Invasive species are a form of non-native species found in the UK. Non-native species are species introduced, usually by human action, outside their natural past or present distribution that might survive and subsequently reproduce.

Therefore, invasive non-native species are those flora or fauna introduced into the UK, which have the ability to spread, causing damage to the environment, the economy, our health and the way we live.

The Wildlife and Countryside Act 1981 contains measures for preventing the establishment of non-native species, which may be detrimental to native wildlife, prohibiting the release of animals and planting of plants listed in Schedule 9 in England and Wales. This schedule is reviewed and updated from time to time.

It’s not an offence to have these species on your land; however you mustn’t allow them to grow in the wild. This can include moving contaminated soil or plant cuttings. It’s also a nuisance offence to allow a certain type of invasive species ‘ Japanese knotweed to grow on other people’s property.

The Weeds Act 1959 classes 5 weeds as injurious. Again it’s not an offence to have these weeds on your land, but you have a legal duty to prevent them spreading to agricultural land, and you must choose the most appropriate method for controlling them if on your site.

Common types of invasive species and injurious weeds

The 5 most widespread types of invasive species are:

  • Japanese knotweed  


  • Giant hogweed


  • Himalayan balsam


  • Rhododendron


  • New Zealand Pigmyweed



The 5 most common injurious weeds are:

  • Common ragwort (most prevalent and dangerous to animals)


  • Spear thistle


  • Creeping or field thistle


  • Broad-leaved dock


  • Curled dock


Disposing of invasive species can be tricky, and if dealt with incorrectly, it can be illegal. So, the advice before you do anything is to contact the regulator, either Natural England or the Environment Agency.