Giant Rhubarb: (Gunnera Tinctoria) is an alien invasive plant that was first introduced to Ireland over 100 years ago as an ornamental plant. It is predominantly found in western coastal counties. With a very heavy infestation on Achill Island, Co Mayo.

Gunnera is a plant native to South America, its natural habitat has very similar climatic conditions to those of the west of Ireland, Gunnera is predominant along roadsides and waterways, on coastal cliffs and disused farmlands and quarries.

Gunnera is a large herbaceous plant that forms dense colonies it can grow up to 2 metres in height. It has large leathery umbrella shaped leaves, with spikes on the back of the leaves and along the stems.

The size of the leaves and their early spring emergence prevent native plants from germinating or growing due to shading. Despite its similar appearance Gunnera is not related to rhubarb.

Gunnera has a large rhizome which can grow up to 2 metres in length along the ground, it can resprout from tiny fragments of the rhizome and can reproduce by seed, and each flower head can produce over 250,000 seeds a year. This allows the plant to spread rapidly and makes it very difficult to eradicate.