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):
To be, or not to be haue,<br> Then flie to others we know not of.<br> Thus conſcience dooes make cowards,<br> And thus the natiue hiew of reſolution<br> Is ſickled ore with the pale caſt of thought,<br> And enterpriſes of great pitch and moment,<br> With this regard theyr currents turne awry,<br> And loose the name of action. Soft you now,<br> The faire "Ophelia", Nimph in thy orizons<br> Be all my ſinnes remembred. "Mr. William Shakespeares Comedies, Histories, & Tragedies", published by Isaac Jaggard and Ed Blount in 1623 and better known as the "First Folio", includes an edition of "Hamlet" largely similar to the Second Quarto. The