This native perennial grows to 6 feet and taller. The erect stem is purple or green with purple spots (A). Extension via its rhizomatous root system often produces colonies. The lance-shaped leaves are in whorls of 4-5. Flattened flower clusters at the top of the stem and upper branches are composed of many cylindrical flower heads (B). Each flower head contains from 8-20 individual purplish-pink disk florets with two long protruding string-like styles (B). Florets mature into small seeds with attached bristly hairs that facilitate wind dispersal.

Very similar Sweet Joe Pye Weed does not have all red or mottled red stems. Its reddish stem color is confined to the area where the whorled leaves join the stem. Other “bonesets” including Boneset,Tall and Late Boneset and False Boneset have similar, usually paler flowers and opposite, not whorled, leaves.