Resembling no. 9 [Eupatorium rugosum Houttuyn.], but more delicate and slender, 3-6 dm, often glabrous throughout; lvs very thin, deltoid or subcordate, about as broad as long, coarsely and irregularly dentate, the petiole nearly or fully as long as the blade; invol bracts attenuate- acuminate. Under overhanging sandstone cliffs; Cumberland Plateau region of s. Ky. and n. Tenn. Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.