Eupatorium bruneri A. Gray in A. Gray et al., Syn. Fl. N. Amer. 1(2): 96. 1884; Eupatoriadelphus maculatus (Linnaeus) R. M. King & H. Robinson var. bruneri (A. Gray) R. M. King & H. Robinson; Eupatorium atromontanum A. Nelson; E. maculatum Linnaeus subsp. bruneri (A. Gray) G. W. Douglas; E. maculatum var. bruneri (A. Gray) Breitung; E. purpureum Linnaeus var. bruneri (A. Gray) B. L. Robinson; E. rydbergii Britton; E. trifoliatum Linnaeus var. bruneri (A. Gray) Farwell
Plants 60–150 cm. Stems densely puberulent throughout (glabrescent at bases). Leaves: petioles pubescent to glabrescent; blades lance-elliptic to lanceolate or lance-ovate, usually 6–17 × 1.5–5(–7) cm, relatively firm, bases gradually or abruptly narrowed, abaxial faces densely hairy (hairs relatively short, spreading); distalmost whorls of leaves directly subtending heads, not surpassing heads. Phyllaries mostly glabrescent, outer sometimes densely pubescent.
The reference to "Joe Pye" appears to likely have been to the Christian name adopted by a Native American herbalist associated with the Stockbridge Mohicans of eastern North America. Used of the term "spotted" refers to purple markings on the stems. "Gravel root" is a term referring to purported medicinal benefits found in the roots.
Eutrochium species have rayless florets and usually have three to seven (three to four in the case of E. maculatum) dark green whorled leaves that are toothed. (Var. bruneri has puberulent stems and abaxial leaves that are pubescent unlike its eastern counterparts.)
The plant is generally aromatic; the seeds of at least the western variety have a very pleasant cinnamon smell.