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 In the Elsinore churchyard, two "clowns", typically represented as "gravediggers", enter to prepare Ophelia's grave. Hamlet arrives with Horatio and banters with one of them, who unearths the skull of a jester whom Hamlet once knew, Yorick. Ophelia's funeral procession approaches, led by Laertes. Hamlet interrupts, professing his own love and grief for Ophelia. He and Laertes grapple, but the fight is broken up by Claudius and Gertrude. Later that day, Hamlet tells Horatio how he escaped death on his journey, disclosing that Rosencrantz and Guildenstern have been sent to their deaths instead. A courtier, Osric, interrupts to invite Hamlet