Stems tall, smooth, often purplish and glaucous, frequently straight, simple or branched only at the summit, 3 to 10 feet high from a perennial root. Leaves ovate, oval or ovate-lanceolate, petioled. toothed, 4 to 13 inches long, one-half to 3 inches wide, veiny and sometimes slightly piibescent on the under side of the leaf, arranged in whorls of threes to sixes, commonly in fours. The inflorescence consists of large, terminal, loose, compound clusters of numerous flower heads, pinkish lavender to purple in color; each head composed of tubular flowers only. Involucres of individual heads cylindric, with pinkish purple, oblong, blunt bracts, overlapping in four or five series.
Memoir 15 N. Y. State Museum
Joe-Pye Weed; Purple Boneset - Eupatoriurn purpureum
In moist soil, woods and low thickets, especially common in wet places along streams, New Brunswick to Manitoba, south to Florida and Texas. Flowering in August and September.
The Spotted Joe-pye Weed (Eupatorium maculatum Linnaeus) is similar to E. purpureum, but the stem is spotted with purple and usually rough or pubescent; the flowers usually pinkish purple in color.