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):
Prince Hamlet and Guildenstern. Alone, Claudius discloses that he is actually sending Hamlet to his death. Prior to embarking for England, Hamlet hides Polonius' body, ultimately revealing its location to the King. Meanwhile, her father's death has driven Ophelia insane with grief, and Claudius convinces her brother Laertes that Hamlet is to blame. He proposes a fencing match between the two. Laertes informs the king that he will further poison the tip of his sword so that a mere scratch would mean certain death. Claudius plans to offer Hamlet poisoned wine if that fails. Gertrude enters to report that Ophelia has died.