We wind up the thoroughwort season with this late entry, whose dusty off-white puffs of raggedy flowers decorate roadsides and railroad rights-of-way in September and October. A close view reveals the inividual flowers that make up each head. This specimen grew through a crack in a disused parking lot in Oakmont.
From Gray’s Manual of Botany: Eupatorium serotinum Michx. Stem pulverulent-pubescent, bushy-branched, 1-2 m. high ; leaves ovate-lanceolate, tapering to a point, triple-nerved and veiny, coarsely serrate, 0.5-1.5 dm. long ; involucre very pubescent. Alluvial ground, Md. to Minn., e. Kan., and south w.