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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.
Giant Rhubarb Leaves
It is recommended that any attempt to control Giant Rhubarb should be carried out by trained and experienced personnel.
European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)
There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...
Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.
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American Skunk-Cabbage - Lysichiton americanus
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Red Alga - Grateloupia doryphora
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Wakame - Undaria pinnatifida
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Water-Primrose - Ludwigia (all species)
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Waterweeds - Elodea (all species)
Additional Non-Native Plant Species identified as Medium Risk on Ireland's Biodiversity List...
Common name
Barberry
Brazilian waterweed
Butterfly-bush
Canadian-fleabane
Clover broomrape
False acacia
Garden lupin
Giant rhubarb
Hairy rocket
Himalayan honeysuckle
Himalayan knotweed
Holm oak
Pampas grass
Pitcherplant
Red oak
Rock cotoneaster
Salmonberry
Sycamore
Three-cornered garlic
Traveler's-joy
Species name
Lysichiton americanus
Antithamnionella ternifolia
Ribes nigrum
Egeria densa
Buddleja davidii
Conyza canadensis
Codium fragile ssp. tomentosoides
Pseudotsuga menziesii
Solidago gigantea
Gunnera manicata
Persicaria wallichii
Lonicera japonica
Euphorbia esula
Acaena ovalifolia
Matteuccia struthiopteris
Sarracenia purpurea
Bunias orientalis
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