Ageratina occidentalis is a rhizomatous perennial herb growing fuzzy green or purple stems to a maximum height near 70 centimeters. Its leaves are glandular and triangular, with serrated edges. The inflorescence is a dense cluster of fuzzy flower heads containing long, protruding disc florets in shades of white, pink, and blue. There are no ray florets. The fruit is an achene a few millimeters long with a rough, bristly pappus.[5]
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.[6]
The name Eupatorium comes from the Greek king Mithridates VI Eupator, who is said to have discovered that a species in the genus could be used as an antidote to a common poison.[7]
^"Ageratina occidentalis". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
^Keil, David J.; Powell, A. Michael (1993). "Ageratina occidentalis". In Hickman, James C. (ed.). The Jepson Manual: Higher Plants of California. University and Jepson Herbaria.
^Gledhill, David (2008). "The Names of Plants". Cambridge University Press. ISBN9780521866453 (hardback), ISBN9780521685535 (paperback). pp 39
^Blackwell, Laird R. (2006). Great Basin Wildflowers: A Guide to Common Wildflowers of the High Deserts of Nevada, Utah, and Oregon (A Falcon Guide) (1st ed.). Guilford, Conn.: Morris Book Publishing, LLC. p. 56. ISBN0-7627-3805-7. OCLC61461560.