Nomenclature and Distribution of Eupatorium ✕ truncatum, with Comments on the Status of E. resinosum var. kentuckiense (Asteraceae)

The synonymy of Eupatiorum ✕ truncatum, the hybrid of E. perfoliatum and E. serotinum, is discussed. Eupatorium resinosum var. kentuckiense is recognized as con-specific with E. ✕ truncatum. A key is provided for E. serotinum, E. perfoliatum, E. resinosum, and E. ✕ truncatum. A description and a summary of the distribution of E. ✕ truncatum are provided.