EUPATORIUM
Eupatorium, genus Eupatorium
(noun) large genus of chiefly tropical herbs having heads of white or purplish flowers
Source: WordNet® 3.1
Etymology
From the genus name.
Noun
eupatorium (plural eupatoriums)
(botany) Any of the genus Eupatorium of perennial herbs.
Source: Wiktionary
Eu`pa*to"ri*um, n. Etym: [NL., fr. Eupator, king of Pontus, said to
have used it as a medicine.] (Bot.)
Definition: A genus of perennial, composite herbs including hemp agrimony,
boneset, throughwort, etc.
Source: Webster’s Unabridged Dictionary 1913 Edition