Note to Romeo and Juliet, 3.2.73: "O serpent heart, hid with a flowering face!"

Romeo and Juliet,
Act 3, Scene 2, line 73.
flowering: i.e., youthful and fair, like the face of the serpent in the Garden of Eden. (The fair face of the serpent can be seen at the top of the engraving.)
                 Detail from the engraving, Adam and Eve, by Marcantonio Raimondi (c. 1480 to c. 1534)
                 Source:                  Wikipedia