Rue (Ruta graveolens). Folk names include herb of grace, mother of the herbs, Ruta, Witch bane, and garden rue. The rue is an evergreen shrub that can grow from two to three feet in height. It bears small, bright, buttonlike yellow flowers in the summer. The leaves are smooth, deeply divided, and have a greenish blue color. The scent of the rue is described as bracing, and the leaves of this plant are covered in oil glands.