Apparently Shakespeare gardened...

Obviously not a proven fact, but Shakespeare does seem to have an extensive 

knowledge of plants. Like this author said:

"Nearly 30 scenes in his plays take place in a garden,
 and his characters seem to know what they're talking 
about when it comes to weeds, trees, flowers and herbs 
and their properties, both medicinal and poetic. 
If Shakespeare didn't garden himself, he probably knew 
many people who did, or who at least knew about plants. 
His son-in-law, John Hall, was a doctor and herbalist 
and most likely had botanical and medical books."
- Kent Steinriede (Full text here)

Now what does this mean to us? This means that all of Shakespeare's 

seemingly random references to flowers are in fact an obscure method of sharing information with his audience. Since people of his time were 

much more familiar with these plants, Shakespeare could identify with 

his peers by including the familiar names within his plays. 

Now on to the question of the day: What's with Ophelia's flowers? The 

following is a list of the plants mentioned in connection with Ophelia 

and what their true meanings are.

Rosemary: constancy, fidelity, and loyalty

Pansy: thoughtful recollection

Fennel: strength

Columbines: cuckoldry and deserted love

Rue: repentance, herb-of-grace

Daisy: gentleness, innocence, loyal love

Violets: modesty and simplicity

(Some of these I got from here and some I borrowed from No Fear Shakespeare, NFS)

As I'm sure you all noticed, there are a couple that particularly stand 

out. For one thing, rosemary and columbines are the exact opposite 

(constancy v. deserted love) and both seem to be in connection with 

Gertrude. Also rue (repentance) and pansy (thought recollection) seem 

relevant to Claudius. NFS translation really helped me see what these 

all meant, since they associated the meaning of the flower with 

whomever Ophelia was giving it to:

OPHELIA There’s fennel for you, and columbines.—There’s rue for you, and here’s some for me. We may call it “herb of grace” o' Sundays.—Oh, you must wear your rue with a difference.—There’s a daisy. I would give you some violets, but they withered all when my father died. They say he made a good end(sings) For bonny sweet Robin is all my joy—

OPHELIA (to GERTRUDE ) Here are fennel and columbines for you—they symbolize adultery. (to CLAUDIUS) And here’s rue for you—it symbolizes repentance. We can call it the merciful Sunday flower. You should wear it for a different reason. And here’s a daisy, for unhappy love. I’d give you some violets, flowers of faithfulness, but they all dried up when my father died. They say he looked good when he died.(sings) For good sweet Robin is all my joy.

So, wowsa! Ophelia knew what was going down in Denmark! She, in all her madness, picks up on the fact that Gertrude is disloyal to her first husband, that Claudius is in need of repentance, and that neither of them is faithful. 

And all this through flowers....

And as a side note, although not a flower, the fact that Ophelia falls from a willow tree is not a coincidence. Known for its healing properties, the willow's leaves and bark were often used as a remedy for aches and fever. I may be stretching it, but maybe Ophelia's "suicide" was an attempt to heal herself from grief over her father's death? Just a thought....