What species?
The eight focal species of this survey are listed below. The first five of these species are aquatic and the last three are riparian species although they are also often found along roadsides and drainage ditches.
| Scientific Name | Common name | |
| 1 | Azolla filiculoides | Water Fern |
| 2 | Crassula helmsii | New Zealand Pigmyweed |
| 3 | Elodea nuttallii | Nuttall’s Waterweed |
| 4 | Hydrocotyle ranunculoides | Floating Pennywort |
| 5 | Myriophyllum aquaticum | Parrot’s Feather |
| 6 | Fallopia japonica | Japanese Knotweed |
| 7 | Heracleum mantegazzianum | Giant Hogweed |
| 8 | Impatiens glandulifera | Himalayan Balsam |
Click on images to view enlarged and titled photos
Why these species?
These eight species were identified as they pose a serious threat to Ireland’s freshwater ecosystems and native biodiversity, a threat recognised from the Environmental Protection Agency’s (EPA) Water Framework Directive – Alien Species Risk Analysis report (2004). Many of these species also wreak havoc on the recreational value of an area and have negative economic consequences for local industries. The species were also amongst the highest scoring in the Invasive Species Ireland 2007 risk assessment procedure. [For more information about the risk assessment please visit the Invasive Species Ireland website]
