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 ἀστήρ (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 186 species as of August 2024. 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. Selected species:

Phytochemical Profile

Hybrids and cultivars

Those marked have gained the Royal Horticultural Society's Award of Garden Merit.

In history

The Hungarian revolution of 31 October 1918, became known as the "Aster Revolution" due to protesters in Budapest wearing this flower.

In culture

One of the few flowers left around Michaelmas in the British Isles is the Michaelmas daisy (another name for asters), hence the rhyme: "The Michaelmas daisies, among dead weeds, Bloom for St Michael's valorous deeds..." In the UK, national collections of asters are held at Old Court Nurseries and Picton Garden in Colwall, near Malvern, Worcestershire. and at Upton House, Warwickshire.