Taxonomy

Gunnera tinctoria | Giant-rhubarb | Gunnaire

Distribution

Status

Conservation status

Not Assessed

Legal status

Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted).

Listed as a schedule 9 species under Articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Article 15A not yet enacted).

Regulated invasive  species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].

First reported in the wild

1939

Invasiveness

Invasive species - risk of High Impact

Irish status

Established

Introduction pathways - 1

Escape from Confinement

Introduction pathways subclass - 1

Ornamental purpose

Invasive score

19

NAPRA Ireland risk assessed

Yes. This species underwent a  Non-native species APplication based Risk Analysis  in 2014.

Overall risk of this species to Ireland is categorised as: MAJOR with a MEDIUM level of confidence.

Overall conclusion summary (Excerpt):  Gunnera tinctoria produces large numbers of seeds, which are dispersed by wind, water and birds; it also spreads clonally, by a horizontal rhizome system (Gioria and Osborne, 2013). Long-distance seed dispersal seems to be central to the colonisation of new areas (Gioria and Osborne, 2013). Dispersal of the species is strongly associated with human activities. It is targeted for eradication but such control measures are known to have failed (Armstrong, 2008; Sheehy Skeffington and Hall, 2011).

The species has the potential to expand its invasive range. Gunnera tinctoria invasions may result in a range of environmental, economic and societal impacts. Of much concern is the impact to indigenous biodiversity, alterations to ecosystem function and the provision of ecosystem services. Control and/or eradication of the species will impact on the Irish economy, particularly in counties Galway and Mayo. 

 View the full risk assessment: http://nonnativespecies.ie/wp-content/uploads/2014/03/Gunnera-tinctoria-Giant-Rhubarb.pdf

Species Biology

Identification

Giant rhubarb', huge herbaceous perennial, leaves greater than 2m across, alternate but clustered and rhubarb like, palmate 5-9 lobed with jagged serrated lobes (Stace, 2002). Examination of the fruit in is necessary to distinguish from Gunnera manicata.

Ecology

Crowds out native plants and significantly alters the seed bank community (Gioria & Osborne, 2009). In areas where Gunnera is present it can represent 53 - 86% of the seedlings (Gioria & Osborne, 2009) and additionally alters the seed bank so that it is dominated by agricultural weeds (Gioria & Osborne, 2009).

Habitat

Coastal; Mires, bogs & fens; Grasslands and landscapes dominated by forbs, mosses or lichens; Inland unvegetated or sparsely vegetated habitats; Constructed, industrial or other artificial habitats; Miscellaneous

Reproduction

Number of fruit ranges from 12 000 to 83 000 borne on 1m infructesences on plants in New Zealand (Williams et al., 2005).

Pathway and vector description

Introduced into Ireland as a garden plant it has since escaped (Reynolds, 2002).

Mechanism of impact

Competition

Management approach

There is currently an EU wide ban on the sale, growing and keeping of this plant (European Commission, 2017). Eradication should be attempted but is difficult because of the large number of seeds produced and the plant's ability to reproduce vegetatively from tiny rhizome fragments (Armstrong et al., 2009). 

Public Awareness

Gunnera tinctoria is a popular garden landscaping plant. Gardeners and other landowners and users should be educated in the identification of this species as well as its ecological impacts. Several Counties have already produced excellent information leaflets. Galway http://biodiversity.galwaycommunityheritage.org/content/places/invasive-species/gunnera and Mayo http://www.mayococo.ie/en/Services/Heritage/GunneratinctoriaGiantrhubarb/

Manual

Smaller plants and sparse infestations can be dug up with spades (Armstrong et al., 2009). Monitoring for regrowth and recolonisation should be carried out within a year (Williams et al., 2005).

Mechanical

Heavy machinery such as mini-diggers or excavators can be used to clear large areas (Armstrong et al., 2009). It is essential to remove the entire rhizome (Williams et al., 2005). Consideration must be given to the disposal of the large quantities of plant material.

Chemical

Glyphosate application is an effective control method (Armstrong et al., 2009). 2,4-d amine and triclopyr are also effective but cannot be used near water. Spraying should be carried out at the end of the growing season before die back (August – September). Repeat applications will be necessary (Williams et al., 2005).

Leaf stalks can be cut and then painted with herbicide. This is useful for large infestations as the removal of the leaves allows better access to the site (Armstrong et al., 2009). Repeat applications will be necessary (Williams et al., 2005).

Herbicides can also be injected by drilling several holes in the rhizome and filling with herbicide (Armstrong et al., 2009). Repeat applications will be necessary (Williams et al., 2005).

Disposal

Armstrong et al. (2009) suggest disposal by deep burial. Mayo County Council (undated) recommends leaving the material to decay in black plastic or drying out and burning. 

Broad environment

Terrestrial

Habitat description

Present in a large range of habitats, such as grassland, waterways, roadsides, quarries, bog, heath, coastal cliffs and agricultural fields (Reynolds, 2002).

Species group

Plant

Native region

South America

Similar species

Gunnera manicata 

Distribution

World distribution(GBIF)

Irish distribution

Established - Widespread. While widespread it is relatively localised with patches of heavy abundance (Reynolds, 2002). Considered invasive on the west coast, possibly due to climatic conditions, with Achill Island having a particularly large abundance.

Native distribution

Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador and Peru.

Temporal change

Date of first record category

1931-1940

Fifty year date category

1901-1950

Records submitted to Data Centre in 2017

The following map is interactive. If you would prefer to view it full screen then click here.

How can you help

Report any sightings to the National Biodiversity Data Centre. Do not purchase or plant in your garden. Dispose of garden waste and nuisance plants responsibly.

References

Publications

Armstrong, C; Osborne, B; Kelly, J and Maguire, CM. (2009). Giant Rhubarb (Gunnera tinctoria) Invasive Species Action Plan. Prepared for NIEA and NPWS as part of Invasive Species Ireland. http://invasivespeciesireland.com/wp-content/uploads/2011/01/Gunnera_tinctoria_ISAP.pdf Site accessed 6 September 2017.

European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.

Gioria, M., & Osborne, B. (2009). The impact of Gunnera tinctoria (Molina) Mirbel invasions on soil seed bank communities. Journal of Plant Ecology, 2(3), 153-167.

Mayo County Council (undated). Invasive Alien Plant Information Leaflet – Giant Rhubarb (Gunnera tinctoria). An action of the County Mayo Heritage Plan 2006–2011. http://www.mayococo.ie/en/Services/Heritage/GunneratinctoriaGiantrhubarb/File,8428,en.pdf Site accessed 6 September 2017.

Reynolds, S.C.P. (2002) A catalogue of alien plants in Ireland. National Botanic Gardens. Glasnevin, Dublin.

Stace, C. (2002). New Flora of the British Isles 2nd Edition. Cambridge University Press, Cambridge.

Williams PA, Ogle CC, Timmins SM, Cock GDLa , Clarkson J, 2005. Chilean rhubarb (Gunnera tinctoria): biology, ecology and conservation impacts in New Zealand. DOC Research and Development Series. Wellington, New Zealand: Department of Conservation.

Invasive Species Ireland Action Plan

CABI Datasheet

DAFM Invasive Plant Information Note for Gunnera tinctoria

Mayo county Council Ginat rhubarb information leaflet

Images