Boltonia asteroides

Native to central Canada and the central and eastern United States, with isolated populations in Idaho and Oregon, this herbaceous perennial grows about 3 to 6 feet tall. Its branching stems carry narrow, gray-green leaves. From late summer into fall, numerous small flower heads have white, sometimes pink or violet rays around yellow centers. It grows in wet prairies, marshes, and beside streams and ponds. It spreads through creeping underground stems and seeds, and tolerates clay and moderately dry soil. Photographed in Virginia, United States.