Ageratina altissima (Asteraceae)
A lesser-grown cousin of well-known thoroughworts like Joe-Pye, Boneset and Blue Mistflower. Clusters of small, furry bright-white flowers from midsummer to frost are a magnet for butterflies. Native throughout the east coast and into the Mississippi Valley, usually found along woods edges and in thickets. Good for naturalizing in larger areas or filling in shady corners; may be deadheaded to prevent seeding into smaller gardens. Grows in rich to rocky soils but prefers moist sites in partial shade. (Formerly Eupatorium rugosum.)
Bloom period: mid-summer
Container size: Qt.