First reported in the wild
Invasive species - risk of Medium Impact
Introduction pathways - 1
NAPRA Ireland risk assessed
Tiny free floating plant, smaller than Lemna minor, having a single leaf midrib, though it may form dense mats (Minchin & Boelens, 2008; Reynolds, 2002)
While there are studies on the negative impacts of other Lemna spp it is difficult to ascertain do these effects apply to Lemna minuta. However in eutrophied lakes and rivers, as L. minuta has a competitive advantage over the native L. minor in water with high nutrient concentrations (Njambuya et al., 2011), so it may displace the native L. minor in polluted water bodies.
Inland surface waters
Not been observed to flower in Ireland, so reproduction is by vegetative means, with plants dispersed by wind (Minch & Boelens, 2008) & waterfowl (Coughlan et al., 2014).
Pathway and vector description
First observed in the wild at 3 locations in 1993, in 2002 it was considered "rare but likely to spread" (Reynolds, 2002), indicating a rapid dispersal since introduction. Possibly introduced as an ornamental or pond species but seems unlikely due to small size, may have been introduced as a contaminant on other aquatic plants (Reynolds, 2002) or may have been carried by waterfowl from Britain (where it has been present since 1977 (Preston et al., 2004)) or the continent (Coughlan et al., 2014).
Mechanism of impact
Competition, Bio-fouling, Other
Slow moving, freshwater including canals, lakes and ponds (Reynolds, 2002).
North America, South America
Established - Widespread, Locally abundant and spreading. Possibly under recorded due to its size.
Native to the temperate and subtropical parts of the Americas, present in Europe since the 1960s (Preston et al., 2004).
Date of first record category
Fifty year date category
Records submitted to Data Centre in 2021
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How can you help
Report any sightings to the National Biodiversity Data Centre.
Reynolds, S.C.P. (2002) A catalogue of alien plants in Ireland. National Botanic Gardens. Glasnevin, Dublin. Preston, C.D., Pearman, D. A. & Dines, T. D. (2002). New atlas of the British and Irish flora. An atlas of the vascular plants of Britain, Ireland, the Isle of Man and the Channel Islands, Oxford University Press. Stace, C. (1997). New Flora of the British Isles 2nd Edition. Cambridge University Press, Cambridge. Minchin, D., & Boelens, R. (2011). The Distribution and expansion of Ornamental Plants on the Shannon Navigation. In Biology and Environment: Proceedings of the Royal Irish Academy. 111(3):195-203. Coughlan, N. E., Kelly, T. C., & Jansen, M. A. K. (2015). Mallard duck (Anas platyrhynchos)-mediated dispersal of Lemnaceae: a contributing factor in the spread of invasive Lemna minuta?. Plant Biology, 17(s1), 108-114. Njambuya, J., Stiers, I., & Triest, L. (2011). Competition between Lemna minuta and Lemna minor at different nutrient concentrations. Aquatic botany, 94(4), 158-164.