Ambrosia artemisiifolia | Ragweed



Conservation status

Not Assessed

First reported in the wild



Invasive species - risk of Medium Impact

Irish status

Occasionally present, casual, vagrant, migratory

Introduction pathways - 1

Transport Contaminant

Introduction pathways subclass - 1

Seed contaminant

Invasive score


NAPRA Ireland risk assessed


Species Biology


Annual, erect stem up to 1m tall, leaves deeply pinnately divided, only 1 greenish flower (Stace, 1997).


Primary impact is as an aeroallergen it produces allergenic pollen, which can induce allergic disease, such as rhinitis, conjunctivitis, asthma and contact dermatitis (Kazinczi et al., 2008), with heavily infested regions suffering high medical costs (e.g. €110 million per year in Hungary), (Kazinczi et al., 2008). Seasonal pollen production per plant ranges from 100 million to 3 billion in France (Fumanal et al., 2007).


Inland unvegetated or sparsely vegetated habitats; Regularly or recently cultivated agricultural, horticultural or domestic habitat


Monoecious plant, with low self compatibity though seed production ranges from 346 to 6,114 in France, depending on plant size and habitat (Fumanal, 2006). Seeds may survive for up to 39 years in the soil if conditions are suitable (Rich, 1996).

Pathway and vector description

Introduced as a contaminant in agricultural and bird seed. (Reynolds, 2002). The western and eastern European populations appear to be genetically distinct indicating separate introduction events, rather than a spread and suggests there are at least two source populations for introduction to Ireland (Gladieux et al., 2010).

Mechanism of impact


Broad environment


Habitat description

Generally found on waste ground though can be a weed of agricultural land (Reynolds, 2002).

Species group


Native region

North America


World distribution(GBIF)

Irish distribution

Occasionally present, casual - Rare, localised with records from 1900 not representing a continuous presence (Reynolds,2002). Based on the climatic conditions in which it occurs in North America it cannot currently persist in the British Isles (Cunze et al., 2013), with populations generally only persisting for 2-3 years (Rich, 1996) but likely to become established in the future due to climate change (Cunze at al., 2013).

Native distribution

Native to the USA and Canada, introduced to Europe, Japan, Australia and Africa (Cunze et al., 2013).

Temporal change

Date of first record category


Records submitted to Data Centre in 2020

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How can you help

Report any sightings to the National Biodiversity Data Centre.

Further information

Delivering Alien Invasive Species In Europe (DAISIE) project listed this species as one of 100 Worst Invaders in Europe.



Reynolds, S.C.P. (2002) A catalogue of alien plants in Ireland. National Botanic Gardens. Glasnevin, Dublin. Stace, C. (1997). New Flora of the British Isles 2nd Edition. Cambridge University Press, Cambridge. Fumanal, B., Chauvel, B., & Bretagnolle, F. (2007). Estimation of pollen and seed production of common ragweed in France. Annals of Agricultural and Environmental Medicine, 14(2), 233. Cunze, S., Leiblein, M. C., & Tackenberg, O. (2013). Range expansion of Ambrosia artemisiifolia in Europe is promoted by climate change. ISRN Ecology, 2013. Gladieux, P., Giraud, T., Kiss, L., Genton, B. J., Jonot, O., & Shykoff, J. A. (2011). Distinct invasion sources of common ragweed (Ambrosia artemisiifolia) in Eastern and Western Europe. Biological invasions, 13(4), 933-944. Rich, T. C. G. (1994). Ragweeds (Ambrosia L.) in Britain. Grana, 33(1), 38-43. Kazinczi G., Béres I., Pathy Z. & Novák R. (2008). Common ragweed (Ambrosia artemisiifolia L.): A review with special regards to the results in Hungary: II. Importance and harmful effect, allergy, habitat, allelopathy and beneficial characteristics. Herbologia 9(1): 93-118.

CABI Datasheet

Global Invasive Species Database

DAISIE Factsheet