Amidst the yellow swaths of sunflowers and and goldenrod are clumps of aster, usually purplish or bluish in color. Though no longer included in the Aster genus (now limited to Eurasian species), New World asters are represented by more than 100 species in North America.
Not keen on scientific labeling, I, like most nature lovers, appreciate asters for their beauty and for their late summer and early autumn blooms, an important resource for pollinators; the clumps in our yard (photo) have been loaded with a wide variety of bees and butterflies.
Missouri is home to 24 species of New World asters, almost all of which are perennials. Like other wildflowers, they do just fine without human supervision.