ageratum ăj˝ərā´təm, əjĕr´ə– [key] [Gr.,=unaging], any plant of the genus Ageratum, tropical American annuals of the family Asteraceae ( aster family). The commonly cultivated species is the Mexican A. houstonianum, with thick terminal clusters of blue flowers. The similar mistflower, a Eupatorium (see boneset ), is a perennial sometimes called hardy ageratum. Ageratum is classified in the division Magnoliophyta , class Magnoliopsida, order Asterales, family Asteraceae.

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