horseweed

(noun) erect perennial strong-scented with serrate pointed leaves and a loose panicle of yellowish flowers; the eastern United States. Synonyms: horse balm, stoneroot, stone-root, richweed, stone root, Collinsonia canadensis.

(noun) common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron. Synonyms: Canadian fleabane, fleabane, Conyza canadensis, Erigeron canadensis.