Aster tataricus

Native from southern Siberia through East Asia to Japan, this perennial herb grows about 3 to 6 feet tall. Its lavender-purple flower heads have yellow centers and bloom late in the growing season. It spreads vigorously through underground rhizomes, forming broad colonies that can be divided to produce new plants. Cultivated as an ornamental, it has become naturalized in parts of the northeastern, north-central, and southeastern United States. Its late flowers provide nectar for butterflies, moths and bees after many other garden plants have finished blooming. Photographed in Virginia, United States.