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Organisation Européenne et Méditerranéenne pour la Protection des Plantes
EPPO Data sheets on invasive alien plants
Fiches informatives sur les plantes exotiques envahissantes
Landoltia punctata (G. Mey) Les & D.J. Crawford
Araceae – Dotted duckweed
Scientific name: Landoltia punctata (G. Mey) D.H. Les & D.J. Crawford (1999).
Synonym: Lemna javanica F.A. Bauer ex Hegelm., Lemna melanorrhiza F. Muell. Ex Kurz, Lemna oligorrhiza (Hegelmaier) Kruz, Lemna pleiorrhiza F. Muell. Ex Kurz, Lemna punctata G. Mey., Lemna pusilla Hegelm.,Spirodela melanorrhiza (F. Muell. Ex Kurz) Hegelm., Spirodela oligorrhiza (Kurz) Hegelmaier,Spirodela oligorrhiza var. javanica Hegelm., Spirodela oligorrhiza var. melanorrhiza (F. Meull. Ex Kurz) Hegelm., Spirodela oligorrhiza var. pleiorrhiza (F. Muell. Ex Kurz) Hegelm., Spirodela oligorrhiza var. pusilla Hegelm., Spirodela pleiorrhiza (F. Muell. Ex Kurz) Hegelm., Spirodela punctata (G. Mey.) C.H. Thomps.(Q-bank 2013).
Basionym: Lemna punctata G. Mey. ,Prin. Fl. Esseq. 262. 
Taxonomic position: Magnoliophyta, Araceae, Lemnoideae, Lemnaceae
Common names: Dotted duckweed, dotted duckmeat, giant duckweed, thin duckweed (English), small kroos (Dutch) geringwurzelige Teichlinse (German), himeukikusa (Japanese).
EPPO code: SPIOL
There is no regulatory status for this species.
L. punctata is native to South-East Asia and Australia.
EPPO region: Netherlands, Italy, Spain, Switzerland.
Africa: Madagascar, South Africa, Zimbabwe
Asia: China, India, Indonesia, Japan, Malaysia, Philippines, Taiwan, Thailand, Vanuatu, Vietnam,
Central America: Belize, Costa Rica, Puerto Rico
North America Alabama, Arkansas, Arizona, California, Florida, Georgia, Oregon, Louisiana, Missouri, Mississippi, Tennessee, Texas, Oklahoma, South Carolina, Pennsylvania, Kentucky, North Carolina, Virginia.
South America: Argentina, Bolivia, Chile, Colombia, Guyana, Venezuela
Oceania: Australia, Fiji, Maldives, Mauritius, New Caledonia, New Zealand
History of introduction and spread
L. punctata was first recorded in the USA in Missouri 1930 (Wisconsin Department of Natural Resources, 2008). In the Netherlands L. punctata was first recorded in 2007. van Valkenburg and Pot (2008) highlight that in Europe the number of recent records are low and some were only temporary.
L. punctata is a freely floating aquatic species
Fronds measure 1.5 to 6 mm in length and 1 -3 mm in width. Fronds are individual, elliptic to obovate and flat on both surfaces. The upper surface is green in colour whereas the lower surface is red to purple (van Valkenburg and Pot, 2008). Each frond has a waxy cuticle and 2 to 5 descending roots submerged in the water.
Biology and ecology
L. punctata reproduces by vegetative budding of the daughter fronds from pouches at the base of each frond. The species can reproduce sexually, by seed, though this is reported to seldomly happen (Wisconsin Department of Natural Resources, 2008). L. punctata grows quickly and rapidly reproduces and spreads. The plant grows well in low oxygen aquatic habitats.
L. punctata grows in nutrient rich aquatic habitats in slow moving stagnant water bodies. L. punctata has the tendency to form dense mats in slow moving water bodies (US Geological Survey Florida Caribbean Science Center, 2001). In China the species occurs in ponds, lakes, pools and ditches up to 2400 m above sea level (Flora of China Editorial Committee, 2012).
L. punctata is frost sensitive. L. punctata plant dies quickly once out of water where the fronds only survive between 0.5 and 21 hours (US Geological Survey Florida Caribbean Science Center, 2001).
Uses and benefits
L. punctata is utilised in nutrient filled waste water ponds to absorb excess nutrients (Chaiprapat et al., 2005). Fang et al. (2007) showed that L. punctata can uptake nitrogen through both the roots and the fronds.
Pathways of movement
Natural dispersal is by water movement and movement by waterfowl or mammals. L. punctata spreads through water bodies by vegetative budding (Hanelt, 2001).
Movement in trade
The plant is reported to have entered into Europe and other areas within its invasive range as a contaminant of the aquatic plant species trade (van Valkenburg & Pots, 2008). In the UK, in 2006, L. punctata was recorded as a contaminant in garden centres (Rumsey, 2006 cited in Lansdown, 2008).
The impact of this plant species is unknown. van Valkenburg & Pot (2008) suggest that it is unlikely that L. punctata will become a nuisance weed in the Netherlands, no different from the range of duckweed species already present. L. punctata has the potential to block irrigation systems when the species forms dense mats on water bodies.
Diquat is used to control L. punctata as it acts to cause ion leakage from the fronds. However, there is evidence that L. punctata can form resistance to chemical herbicides (Koschnick et al., 2006). In a study conducted in the USA, L. punctata was shown to develop resistance to diquat and paraquat herbicides.
Chaiprapat S, Cheng JJ, Classen JJ, Liehr SK (2005) Role of internal nutrient storage in Duckweed growth for swine wastewater treatment. Transactions of the ASAE 48(6), 2247–2258.
Fang YY, Babourine O, Rengel Z, Tang XE, Pu PM (2007) Ammonium and nitrate uptake by the floating Landoltia punctata. Annals of Botany 99, 365–70.
Flora of China Editorial Committee (2012) Flora of China Web. Cambridge, USA: Harvard University Herbaria. http://flora.huh.harvard.edu/china/ [accessed in March 2015]
Koschnick TJ, Haller WT, Glasgow L (2006) Documentation of Landoltia (Landoltia punctata) resistance to diquat. Weed Science 54(4), 615–19
Lansdown RV (2008) Red Duckweed (Lemna Turionifera Landolt) new to Britain. Watsonia 27, 127–30.
Les DH & Crawford DJ (1999) Landoltia (Lemnaceae). A new Genus of Duckweeds. Novon 9, 530–33.
Q-bank (2013) Comprehensive databases of quarantine plant pests and diseases.” http://www.q-bank.eu/ [accessed in March 2015]
Rumsey, FJ (2006) Spirodela punctata – the next invasive Duckweed? Poster Presented at the 2005 Exhibition Meeting of the Botanical Society of the British Isles.
USDA-NRCS (2008) The PLANTS Database. National Plant Data Center. http://plants.usda.gov/ [accessed February 2015]
Van Valkenburg JLCH & Pot R (2008) Landoltia punctata (G. Mey.) D.H.Les & D.J. Crawford (Smal kroos), Nieuw Voor Nederland. Gorteria 33, 41–79.
Wisconsin Department of Natural Resources (2008) Dotted duckweed aquatic plant.” http://dnr.wi.gov/topic/Invasives/documents/classification/Landoltia punctata.pdf. [accessed February 2015]
Landoltia punctata (G. Mey) D.H. Les & D.J. Crawford (Photo J.L.C.H. van Valkenburg)