Prepared by Jennifer L. D’Appollonio, Assistant Scientist, University of Maine, Orono, ME 04469. Updated February 2018. Scientific name: Conyza canadensis (L.) Cronquist; also Erigeron canadensis L. Common name(s): Canadian horseweed, horseweed, Canadian fleabane, Canada fleabane, coltstail, marestail, butterweed Links: USDA PLANTS Profile, Go Botany Images: (to see enlargements [PC]: click on image, then right click