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):
Ophelia arms one last time and proclaims how much he loved her. Hamlet, nearby, then challenges Laertes and claims that he loved Ophelia more than "forty thousand" brothers could. After her funeral scene, Ophelia is no longer mentioned. While it is known that Richard Burbage played Hamlet in Shakespeare's time, there is no evidence of who played Ophelia; since there were no professional actresses on the public stage in Elizabethan England, we may assume that she was played by a boy. The actor appears to have had some musical ability, as Ophelia is given lines from ballads such as "Walsingham" to