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 that we know not of.<br> Thus conscience does make cowards of us all,<br> And thus the native hue of Resolution<br> Is sicklied o'er, with the pale cast of Thought,<br> And enterprises of great "pitch" and moment, [F: "pith"]<br> With this regard their Currents turn "awry", [F: "away"]<br> And lose the name of Action. Soft you now,<br> The fair Ophelia? Nymph, in thy Orisons<br> Be all my sins remember'd. The "First Quarto" (Q1) is the earliest edition of "Hamlet" but is considered a bad quarto (essentially a theatrical knock-off) rather than a first or earlier draft, and although some parts of