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 new King of Denmark and also Hamlet's uncle and stepfather, about the situation. Polonius later suggests to Claudius that they hide behind an arras to overhear Hamlet speaking to Ophelia, when Hamlet thinks the conversation is private. Since Polonius is now sure that Hamlet is lovesick for Ophelia, he thinks Hamlet will express his love for her. Claudius agrees to try the eavesdropping plan later. The plan leads to what is commonly called the "Nunnery Scene", from its use of the term "nunnery" which would generally refer to a convent, but at the time was also popular slang for a