The correct taxonomic position ofSolidago ptarmicoides(Nees) Boivin has long been debated. The abundance of hybrids between this taxonand species ofSolidago, especially species of Sect.Oligoneuron, suggests an affinity with this group. The white colour of florets in this taxon could be due to a mutation interfering with synthesis of the flavonoids accounting for the yellow color inSolidago. In our study of the genusAster, we found that phyllary morphology is a very clear character for excludingA.ptarmicoidesfrom the genusAsterand including it intoSolidago. This conclusion is suported by other morphological features, such as habit and leaf anatomy, and is strengthened by geographical, ecological, and chromosomal data. It is, therefore, suggested that this taxon be definitely removed from the genusAsterand included inSolidagoSect.Oligoneuron. The following new combination is proposed:Solidago×luteus(= ×Solidaster hybridus, ×S.luteus).Solidasterand ×Asteragoare reduced to synonyms underSolidago.