mugwort vs. wormwood

any of certain weedy composite plants of the genus Artemisia, especially A. vulgaris, having aromatic leaves and small, greenish flower heads.

any composite herb or low shrub of the genus Artemisia.

a bitter, aromatic plant, A. absinthium, of the Old World, used as a vermifuge and a tonic, and as an ingredient in absinthe.

something bitter, grievous, or extremely unpleasant.