Symphyotrichum is a genus of over 100 species and naturally occurring hybrids of herbaceous annual and perennial plants in the composite family, Asteraceae, most which were formerly treated within the genus Aster. The majority are endemic to North America, but several also occur in the West Indies, Central and South America, as well as one species in eastern Eurasia. Several species have been introduced to Europe as garden specimens, most notably New England aster and New York aster.

Astereae is a tribe of plants in the family Asteraceae that includes annuals, biennials, perennials, subshrubs, shrubs, and trees. They are found primarily in temperate regions of the world. Plants within the tribe are present nearly worldwide divided into over 250 genera and more than 3,100 species, making it the second-largest tribe in the family behind Senecioneae.