Most Unwanted: Giant rhubarb
Gunnera tinctoria
Habitat: Terrestrial
Threat: Threatens protected species and habitats
Status: Established
Gunnera tinctoria or giant rhubarb is not related to rhubarb, but as its name implies it is similar in appearance. This is a much larger plant with thorny leaves and stems. This is a large herbaceous plant that forms dense colonies and shades out other plants. It persists in the environment and is easily spread either intentionally by gardeners or unintentionally as a contaminant of soil.
What is it?
This plant is most conspicuous in spring and summer when it can grow up to 2 m tall with large ‘umbrella’ shaped leaves that arise from sturdy stalks or petioles. Gunnera over winters as large buds accumulating on the rhizomes (roots) above the surface, while the leaves die back, exposing these buds.
In Ireland it is now found on coastal cliffs, waterways, roadsides, wet meadows and derelict gardens and fields. It propagates both by seed and by vegetative means. In early spring its leaves begin to grow and in a couple of weeks can reach over 2 meters in height.
Impact
Gunnera reduces the biodiversity value of infested sites. It can lead to the local extinction of some species with the formation of almost monospecific stands of gunnera. Elsewhere, this species has also caused problems by blocking drainage ditches and also access ways for people.
Where is it from?
Native to South America but is now invasive in Europe, North America, New Zealand and Australia.
Where are they in Ireland?
The species is currently considered invasive on the west coast of Ireland, although it is also found on the east coast to date it is not considered invasive. It is considered to be having a significant impact on Achill Island, County Mayo, where is has spread throughout.
How did it get here?
The plant arrived in Ireland as an ornamental plant for gardens.
How are they spreading in Ireland
Escape from gardens.
Spread by disposal of garden waste.
Contamination of soil.
What you can do
Report all sightings.
Do not dispose of garden waste containing Gunnera.
Avoid moving soil that is contaminated with Gunnera.
