Ageratina thyrsiflora

Ageratina thyrsiflora is a North American species of plants in the family Asteraceae. It is native mostly to northwestern Mexico. The range extends just barely into the United States, a single herbarium specimen having been collected in 1929 just north of the border town of Nogales, Arizona.

Etymology

Ageratina is derived from Greek meaning 'un-aging', in reference to the flowers keeping their color for a long time. This name was used by Dioscorides for a number of different plants. Thyrsiflora is derived from the Ancient Greek thyrsos and the Latin floris, and so, thyrsiflora means approximately 'with flowers arranged in the shape of a contracted panicle or thyrsos staff'.