Lemna minuta | Least Duckweed



Conservation status

Not Assessed

First reported in the wild



Invasive species - risk of Medium Impact

Irish status


Introduction pathways - 1


Invasive score


NAPRA Ireland risk assessed


Species Biology


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

Broad environment


Habitat description

Slow moving, freshwater including canals, lakes and ponds (Reynolds, 2002).

Species group


Native region

North America, South America


World distribution(GBIF)

Irish distribution

Established - Widespread, Locally abundant and spreading. Possibly under recorded due to its size.

Native distribution

Native to the temperate and subtropical parts of the Americas, present in Europe since the 1960s (Preston et al., 2004).

Temporal change

Date of first record category


Fifty year date category


Records submitted to Data Centre in 2023

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.



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.

CABI Datasheet