What's the meaning of this Hamlet quote: "There's rosemary, that's for remembrance..."?

In act 4, scene 5, Ophelia is depicted as mentally unstable as she enters the scene singing fragments of songs about chaos, death, and unrequited love. Laertes then enters the scene and sees his mentally ill sister for the first time, which only exacerbates his rage. As Ophelia rambles incoherently, she shows Laertes her bundle of flowers and begins to distribute them among those in attendance. Ophelia gives her brother flowers and tells Laertes,

There’s...

In act 4, scene 5, Ophelia is depicted as mentally unstable as she enters the scene singing fragments of songs about chaos, death, and unrequited love. Laertes then enters the scene and sees his mentally ill sister for the first time, which only exacerbates his rage. As Ophelia rambles incoherently, she shows Laertes her bundle of flowers and begins to distribute them among those in attendance. Ophelia gives her brother flowers and tells Laertes,

There’s rosemary, that’s for remembrance. Pray you, love, remember. And there is pansies, that’s for thoughts (Shakespeare, 4.5.151-153).

The flowers that Ophelia gives each character have symbolic meaning and correlate with each character's specific circumstance. Ophelia ends up giving her brother rosemary and pansies, which symbolize remembrance and thought. Ophelia is probably distributing the rosemary to Laertes as a token of her love for him. She may have already made up her mind to commit suicide, and she may want to give Laertes something to remember their close, affectionate relationship. Ophelia may also want her brother to remember her as a healthy, vibrant woman instead of a depressed, confused person in anguish.  Similar to the flowers Ophelia distributes, she too is delicate, fragile, and beautiful. In act 4, Scene 7, Gertrude announces that Ophelia drowned in a brook surrounded by beautiful flowers, which floated around her body.