Taxonomy

Acaena ovalifolia | Two-spined Acaena

Distribution

Status

Conservation status

Not Assessed

Legal status

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

First reported in the wild

1921

Invasiveness

Invasive species - risk of Medium Impact

Irish status

Established

Introduction pathways - 1

Escape from Confinement

Introduction pathways subclass - 1

Ornamental purpose

Invasive score

14

NAPRA Ireland risk assessed

No

Species Biology

Identification

Perennial plant, stems woody at the base but herbaceous distally, leaves pinnate, mat forming, typical less than 15cm (Stace, 1997). Distinguished from Acaena nocae-zelandie by leaflets, the apical pair are 10-30mm with 17-23 teeth (Stace, 1997).

Ecology

Thought to impact heavily on native vegetation in the island of Juan Fernandez in South America (Tyrie, 2008) but no impacts are recorded for Ireland. As it is a densely matting plant it has the potential to smother and outcompete native vegetation (Tyrie, 2008).

Habitat

Woodland, forest and other wooded land; Inland unvegetated or sparsely vegetated habitats; Grasslands and landscapes dominated by forbs, mosses or lichens

Reproduction

Reproduced by seed but can also reproduce vegetatively through a creeping and rooting rhizome system (Tyrie, 2008). Fruit dispersed by attaching to clothes, animals etc. via long spines (Tyrie, 2008).

Pathway and vector description

Grown in gardens as a rockery plant, introduction into the wild was likely as a result of discarded garden waste or as seeds attached to clothing or animals (Tyrie, 2008).

Mechanism of impact

Competition

Broad environment

Terrestrial

Habitat description

Found in woodland, forestry plantations and tracks, sand dunes, railway embankments and other bare ground (Tyrie, 2008).

Species group

Plant

Native region

South America

Similar species

Acaena novae-zelandiae - Pirri-pirri-bur

Distribution

World distribution(GBIF)

Irish distribution

Established - Widespread.

Native distribution

Native to south America, though considered naturalised in Britain (Stace, 1997)

Temporal change

Date of first record category

1921-1930

Fifty year date category

1901-1950

Records submitted to Data Centre in 2020

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How can you help

Report any sightings to the National Biodiversity Data Centre.

References

Publications

Tyrie, C. (2008). Acaena ovalifolia In: Invasive Alien Species in Northern Ireland. National Museums Northern Ireland [Online]. 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.

Invasive Alien Species in Northern Ireland

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