The authors originally identified the strain of duckweed studied in Barks and Laird () as Lemna minor. Subsequent DNA barcoding demonstrated that it was in fact Lemna turionifera (see Supplementary Appendix S2 in Barks et al.). The two species are difficult to distinguish based on morphology (Landolt, p. 275). This change is consistent with recently altered reports issued by the Alberta Biodiversity Monitoring Institute (http://abmi.ca/) regarding the presence of Lemna species in Alberta, Canada. The GenBank sequences associated with the strain (‘Water Building A’) used in Barks and Laird () are MG000422 (atpF-atpH marker) and MG000496 (psbK-psbI marker). This change in species identification from L. minor to L. turionifera also affects Barks () thesis chapters 3 and 5 (the other chapters have correct species identifications except when referring to chapters 3 and 5). This change does not affect Barks and Laird (). That study used strain ‘CPCC 492’ from the Canadian Phycological Culture Centre. It was originally identified as L. minor, and subsequent DNA barcoding confirmed this identification (see Appendix S2 in Barks et al.). The hypotheses tested and the conclusions drawn are unchanged and apply equally well to L. turionifera as they did to L. minor. The authors apologize for any inconvenience caused by this error. Correspondence: Patrick M. Barks, Department of Biology, University of Southern Denmark, 5230 Odense M, Denmark. e-mail: email@example.com.