Giant Rhubarb - Invasive Species Information

What Is Giant Rhubarb - (Gunnera manicata)?

Habitat: Shade tolerant, prefers damp soil.
Distribution in Ireland: Western Ireland

Status: Established

Family name: Gunneraceae

Common Name: Brazilian Giant Rhubarb

birds, water and human activity such as the transport and movement of soil containing the seeds.

Reproduction: reproduce by both sexual (seed) and asexual (vegetative) means. Each mature plant is capable of producing up to 250,000 drupe-like seeds every year which are then distributed by

Giant rhubarb can also regenerate from root fragments, leaf cuttings and rhizomes. Once a small fragment of rhizome becomes established, it can extend by 15cm a year. Please note that breaking the rhizome may result in the creation of more plants.

Giant Rhubarb Seeds

Giant Rhubarb

Giant rhubarb is a large perennial plant which is native to Chile and Argentina in South America. It was first introduced to Ireland in the 1800s as an ornamental garden plant because of its size and exotic appearance. Since then, it has escaped into the wild and is now particularly invasive along the western coast.

How To Identify Giant Rhubarb?

Leaf: Very Large Dark Green Leaf

Seeds: Green/Orange

Size: Can grow to 3 metres high and 4 metres wide

Stem, weak spines on stem and under leaf

Giant Rhubarb is shade tolerant so it may colonise in a variety of landscapes.

The dense stands of Giant Rhubarb can render large areas unsuitable for agricultural or amenity purposes.

Giant Rhubarb - Gunnera manicata ID Guide

The species can invade native grassland and subsequently reduce the value of the land for grazing.

Why Is Giant Rhubarb A Problem?

Giant Rhubarb threatens indigenous biodiversity. Once established, it can quickly develop large and dense colonies which prevent native plants from growing underneath them.

Giant Rhubarb is an invasive species which can seriously effect drainage and water run-off, leading to increase flood risks.

Small fragments of plant material may be spread unintentionally on shoes and clothes.

As the plant is capable of regeneration from small pieces of rhizome, all material must be handled and disposed of in a way which does not result in the potential for further spread.

Management, Control and eradication requires continued input and follow-up over a number of years to deal with re-growth and subsequent seedling germination.