Aster amellus L. (Asteraceae) is a polymorphic aggregate of taxa. The species aggregate is distributed through Central and Eastern Europe and Western Asia. The habitats of the species include grasslands, clearings, edges, slopes, waysides and open forests. Typical habitats of this species have declined over the last decades, and A. amellus became endangered in many parts of Central Europe. This paper deals with taxonomy, morphology, distribution, habitat requirements, life cycle and biology of this species. Special emphasis is given to the differences between diploid and hexaploid plants, which co-occur in Central Europe.