Ophelia represents youth and the innocence that comes with it. Dominated by her father and spurned by Hamlet she succumbs to madness. Viewed as a pathetic character, Ophelia is seen as passive through having no voice to express herself. The flowers she hands out however, are laden with meaning and thus indirectly she could be argued to be extremely intelligent and articulate. How women functioned in such a male dominated world is of particular interest in deciphering the character of Ophelia. Lastly, her apparent suicide by drowning could be said to perfectly symbolize her passivity to nature, or a strong willpower in choosing to die. Read the enotes character analysis for more information and the following article on flower symbolism in the play.
There are many similarities between Hamlet and Richard II. One of their common themes is the allegory of garden stewardship. This theme is more prominent in Richard II. In Hamlet it is more subtle. A healthy and productive garden is the result of deliberate and competent stewardship. Richard II deals with the failings of the King in his role as steward. In Hamlet the argument is that each man has a duty or burden beyond his own self-interest. At this level in the play, Claudius, Polonius, Laertes and even Hamlet have a responsibility given their positions in this garden that is the state of Denmark. In the garden, Ophelia represents the "flower" of Denmark. As such she directly reflects their care. Accordingly, she has no mind of her own. All Ophelia's lines are reflections of the attention she receives from others.
When Hamlet leaves and her father dies, she is left with little rational mind. Finally at the point in the play when Claudius successfully turns Laertes to the dark side in 4.7, Ophelia's mind is completely gone. She dies from too much water, i.e., inept stewardship.