Sub-category: Aster family
Smooth aster is 20 to 70 cm tall. Its leaves are arranged alternately on the stems, and their shape varies between lanceolate, oblong-ovate, oblong-obovate, and ovate. They measure from 30 to 200 mm long and from 10 to 25 mm wide. They are usually hairless, and the leaf edges are entire or bluntly or sharply toothed (crenate or serrate), sometimes with smaller teeth (serrulate). The flower heads are arranged in clusters (panicles). Each flower head has 13 to 23 ray florets with pale to dark blue or purple petals (laminae), and 19 to 33 disc florets that start out yellow and eventually turn purplish-red. The whole flowerhead measures 1.3 to 2.5 cm across.
It is found naturally occurring in fields, open woods and along roadsides. It grows in rocky or dry soil in full sun.