The two main invasive weeds that are most likely to cause problems on development sites in the UK are Himalayan balsam and giant hogweed, which are both introduced, alien species. These plants and a summary of their control options are discussed below. Also discussed below are some of the other, terrestrial plants that can cause problems on development sites.
There are also a number of introduced aquatic plant species that can cause significant problems in ecologically sensitive waterways. However, these most usually affect protected areas of conservation value that are less likely to be affected by development and for his reason they are not discussed in detail here. Defra has produced guidance on invasive species that is available for download at their website about invasive weeds legislation.
Some of the more common invasive aquatic plant species include: floating pennywort; New Zealand pygmyweed; and parrot’s feather.