In Japan, giving cut flowers to a hospital patient is a social blunder, because flowers degenerate and die. You're supposed to give a potted plant the patient can take home. In the Occident, men buy flowers for women out of guilt or obligation. When a woman buys them for a man, she's a classy flirt but also a suspected dominatrix.

If you do buy cut flowers, choose by scent rather than sight. Carnations often smell good, and are inexpensive. Use the $15 difference between roses and carnations to buy her a second gift with more longevity, like an antique crystal vase, a cobalt bottle of rose water, a cast iron butter melter or a Victoronix knife. Never ever give artificially colored flowers. An Edible Arrangement will impress her, but set you back $100 and send the message you're careless with money.

Don't give flowers when they're expected: Valentine's and Mothers' Day; surprise her when they're unexpected. Having them delivered to her office is a fashion statement.

Although I have recieved flowers, I have given them far more often than I've recieved them. I have met women who claim that they don't want to receive flowers because "they die". What a load of horse shit. Ever sent flowers to a sick person, a person recovering from an operation, or to someone...like an elder neighbor? Somethimes that provides far more than a one of life's little pleasures.

You can never go wrong by letting someone know that you're thinking about them. It doesn't have to be flowers, but seeing their signature on that card is special.

I've never been a huge fan of flowers as a gift, regardless of whether I'm giving or receiving them. Sorta as generic as you can get with the added bonus of an expiration date. I can usually come up with something more thoughtful for holidays where flowers dominate the market like mother's day.

My cat also likes to eat flowers and plants, which makes the process of receiving a bouquet a huge pain in the ass because I have to play a game of keep away with things he likes to destroy when I'm out of the apartment.

I agree with Lix that a visit to a botanical garden is vastly preferable.

If they're wildflowesr (including pretty weeds)... all the better if you have to decorate a styrofoam cup to hold 'em.   Forget it, don't pick a flower, take your loved one to a garden.