Symphyotrichum oolentangiense, commonly called sky blue aster, azure aster or blue devils, is native to prairies, fields, wood margins and rocky slopes from Ontario and New York to Minnesota south to Georgia, Alabama and Texas. In Missouri, it is found in scattered locations throughout the State (Steyermark). It is a rhizomatous perennial that typically grows 2-3’ tall. Daisy-like flowers (.5 to 1” across) with blue to blue-violet rays and yellow center disks bloom in many-flowered panicles in September and October. Ovate-lanceolate to oblong lower basal leaves (to 5” long) are rough-hairy, often serrate and cordate at the base. Lanceolate upper leaves are much smaller, narrower and sessile. Flowers are attractive to butterflies. This aster is synonymous with and formerly known as Aster azureus. Some authorities now designate it as Symphyotrichum oolentangiensis. -- https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=d209