Ruta graveolens the isolation of the furanocoumarin chalepensin. The essential oil of "R. graveolens" contains two main constituents, undecan-2-one (46.8%) and nonan-2-one (18.8%). The bitter taste of its leaves led to rue being associated with the (etymologically unrelated) verb "rue" "to regret". Rue is well known for its symbolic meaning of regret and it has sometimes been called "herb-of-grace" in literary works. It is one of the flowers distributed by the mad Ophelia in William Shakespeare's "Hamlet" (IV.5): It was planted by the gardener in "Richard II" to mark the spot where the Queen wept upon hearing news of Richard's capture (III.4.104–105):
Hamlet Fortinbras. Claudius also scolds Hamlet for continuing to grieve over his father, and forbids him to return to his schooling in Wittenberg. After the court exits, Hamlet despairs of his father's death and his mother's hasty remarriage. Learning of the ghost from Horatio, Hamlet resolves to see it himself. As Polonius's son Laertes prepares to depart for a visit to France, Polonius gives him contradictory advice that culminates in the ironic maxim "to thine own self be true." Polonius's daughter, Ophelia, admits her interest in Hamlet, but Laertes warns her against seeking the prince's attention, and Polonius orders her to