BITTERWEED

noun Date: 1819 any of several American plants containing a bitter substance: as, either of two ragweeds:, a low-growing common ragweed ( Ambrosia artemissiifolia ), horseweed , an annual yellow-flowered sneezeweed ( Helenium amarum syn. H. tenuifolium ), an erect annual composite herb ( Hymenoxys odorata ) of the southwestern United States that has yellow flowers and is poisonous to livestock