Aster is a genus of perennial flowering plants in the family Asteraceae. Its circumscription has been narrowed, and it now encompasses around 170 species, all but one of which are restricted to Eurasia; many species formerly in Aster are now in other genera of the tribe Astereae. Aster amellus is the type species of the genus and the family Asteraceae. The name Aster comes from the Ancient Greek word (astḗr), meaning "star", referring to the shape of the flower head. Many species and a variety of hybrids and varieties are popular as garden plants because of their attractive and colourful flowers. 'Aster' species are used as food plants by the larvae of a number of Lepidoptera species—see list of Lepidoptera that feed on Aster. Asters can grow in all hardiness zones. Circumscription The genus Aster once contained nearly 600 species in Eurasia and North America, but after morphologic and molecular research on the genus during the 1990s, it was decided that the North American species are better treated in a series of other related genera. After this split there are roughly 180 species within the genus, all but one being confined to Eurasia. The New World species have now been reclassified in the genera Almutaster, Canadanthus, Doellingeria, Eucephalus, Eurybia, Ionactis, Oligoneuron, Oreostemma, Sericocarpus and Symphyotrichum, though all are treated within the same tribe, Astereae. The "China aster" is in the related genus Callistephus. Regardless of the taxonomic change, most are still widely referred to as "asters", or "Michaelmas daisies", because of their typical blooming period. Species Plants of the World Online accepts 10 species, as of June 2022. The species formerly known as Aster tripolium (sea aster) is now Tripolium pannonicum. The species formerly known as Aster linosyris (goldilocks) is now Galatella linosyris. Many species and a variety of hybrids and varieties are popular as garden plants because of their beautiful, attractive and colourful flowers. Aster species are used as food plants by the larvae of a number of Lepidoptera species—see list of Lepidoptera that feed on Aster. Asters can grow in all hardiness zones. Some species are: Aster ageratoides – rough-surface aster Aster alpinus – alpine aster Aster altaicus Aster amellus – European Michaelmas daisy, Italian aster Aster arenarius – beach-sand aster Aster bellidiastrum Aster fastigiatus – highly-branch aster Aster glehnii – Ulleungdo aster Aster hayatae – Korean montane aster Aster hispidus Aster iinumae – perennial false aster Aster