The author discusses the occurrence of three species of Aster: A. lanceolatus Willd., A. salignus Wildd. and A. tradescantii L. In the Netherlands it is possible, contrary to the views of P.F. Yeo in Flora Europaea4, to recognise A. tradescantii as a species separate from A. lanceolatus. The Netherlands material of A. tradescantii resembles American material of this species. An extensive description of the Netherlands material is in good accordance with descriptions in American flora's. Also, determination of this material with American flora's never gives serious problems. A. salignus does not occur in the Netherlands. In the material formerly identified on this species there are two types of specimens. The specimens with a rusty coloured pappus belong to A. laevis L. or one of its hybrids; those with a dirty white pappus to either A. lanceolatus or A. tradescantii.