In members of Myosotis ser. Palustres Popov occurring in the Netherlands 3 distinct taxa can be distinguished on the basis of karyological, morphological and ecological studies: 1 M. palustris (L.) L. subsp. palustris, palustris, M. palustris subsp. nemorosa (Besser) C. C. Berg & Kaastra, stat. nov. et comb. nov., and M. laxa Lehmann subsp. cespitosa (C. F. Schultz) Hylander ex Nordhagen. Distribution maps and a key to these taxa are given. The chromosome numbers are: 2n = 22 and 44 (endoploid) for M. palustris subsp. nemorosa; 2n = 64 and 66 for M. palustris subsp. palustris; 2n = 88 for M. laxa subsp. cespitosa; 2n = 55 for a putative hybrid of M. palustris subsp. nemorosa and M. laxa subsp. cespitosa.