Symphyotrichum cordifolium, syn. Aster cordifolius (common names common blue wood aster, blue wood-aster or heartleaf aster), is a species of flowering plant in the family Asteraceae, native to eastern North America. An herbaceous perennial, it can be readily found along forest edges and in open areas, as well in urban areas and in cultivation. It sometimes produces a naturally occurring hybrid with S. puniceum named Symphyotrichum × tardiflorum where their ranges overlap. The composite flowers, which typically have bluish to rarely white ray florets and light yellow disc florets that eventually turn purple, emerge in August and persist into October.