The plays of Shakespeare are filled with references to herbs and flowers.
“There’s fennel for you and columbines. There’s a daisy. I would give you some violets, but they withered all when my father died.”
In "Hamlet," when Ophelia mentions flowers, Shakespeare was making statements that probably were quite obvious to his audiences.
In Elizabethan times, fennel was the symbol of flattery, while columbines signified marital infidelity and ingratitude. Daisies were symbols of unhappy love.
Curiously, the columbines in England are blue, while at Interlochen, they are red, and there is a reason.
Here in the Americas, columbines are pollinated by hummingbirds, creatures strongly attracted by the color red. Hummingbirds do not live in Europe, so to attract insects (which do not respond the red end of the spectrum), English wildflowers are more likely to be blue or violet.
When Shakespeare mentioned violets (which he did 18 times), the term was used for any sweet-smelling flower.
Violets were the symbol of loyalty. Not a bad symbol, because these plant are perennials, loyally blooming in the same place each year.
I don’t think Ophelia was a naturalist. She wove garlands using nettles. When she spoke of flowers, she probably wasn't discussing botany but rather was revealing her somewhat troubled true feelings.