This is one of the more common of the native, perennial, blue or purple-colored asters, but can be tricky to distinguish from related species. It is best distinguished from other similar species by looking at the leaves. They are shorter than other similar species - oval or oblong in shape - and the base of the leaf encircles the sometimes purplish stem. The leaves are toothless. The form of the leaf is key to identification of this species.

The flowers are mostly single and found at the end of slender small branches. There are 15-30 ray flowers that resemble petals. The central disk is yellow. The bracts underneath the flower head are sticky and rough with spreading tips. The plant grows 1-3 feet high at the edges of woods, along banks and in moist thickets. It grows in the eastern United States from Massachusetts west to Minnesota and Texas. It blooms from August to October. It is also called the spreading aster.

This aster is most likely to be mistaken for the New England aster (S. novae-angliae) that also has clasping leaves, but has deeper violet flowers with more rays and lance-shaped leaves. The crooked-stemmed aster (S. prenanthoides) also as purple flowers and leaves that clasp the stem, but has a stem that radically changes direction at each node. The flowers of the crooked-stemmed aster are also paler in color and the leaves may have a few teeth along the upper half of their margins. This can be tricky because many plant stems change direction slightly at the nodes.