Asters (Symphyotrichum)
There are as many as 24 native species of asters in the genus Symphyotrichum found in Wisconsin, blooming in hues of white, blue, red, and purple. These highly variable annual and perennial wildflowers range from one to six feet tall and one to four feet wide. Asters thrive in diverse habitats—exposed hillsides, prairies, bluffs, and moist woodlands—and tolerate a range of soils from slightly acidic to alkaline, preferring free-draining conditions, especially in winter. While they need full sun to flower profusely, they can tolerate partial shade during hot spells.
Ecologically, asters are keystone late-season nectar and pollen sources, supporting native bees, butterflies, and hoverflies when few other plants are in bloom. Several species, such as New England aster (S. novae-angliae) and Calico aster (S. lateriflorum), are especially valuable to specialist bees and serve as larval host plants for butterflies and moths including the Pearl Crescent (Phyciodes tharos), Silvery Checkerspot (Chlosyne nycteis), and Isabella tiger moth (Pyrrharctia isabella). Their seeds also feed birds in fall and winter, and their dried stems offer shelter for overwintering insects—making asters not just beautiful, but vital to Wisconsin’s biodiversity. (SF)