This native perennial aster is fairly easy to identify because of its sharp-toothed broad, heart-shaped leaves, often deeply notched at their base. Because it is a variable species, it can be mistaken for the large-leaved aster that has much bigger leaves and for Schreber’s aster which has white flowers and a more blunt indentation at the petiole. The heartleaf aster has composite flowers ½ to 5/8 inch in diameter, formed in dense dome-shaped clusters. The 14-20 central disc flowers turn red early while the 8-15 ray flowers are pale blue-violet. The floral bracts are smooth, narrow, and blunt. The upper leaves may lack the deep notch of the lower leaves and may be more oval in shape.

The heartleaf aster grows one to four feet tall and blooms between August and October. It is found in rich moist soil of open woods and clearings in sun or shade. It grows in southern Canada and the northeastern United States but can be found further south in the mountains. It can be found growing in most counties of Western Pennsylvania. A variety of insects, including bumblebees, visit the flowers for nectar. It is also called the blue wood aster.