Flowers have a language of their own, a bright particular language, that is fun to explore.
Almost all women like flowers. They like to receive many flowers even if is her birthday or an anniversary or for no reason at all. The woman consider that it doesn't really have to be a special day to bring her flowers, it should happen in any simple day in order to show your feelings for her.
If you didn't bring her flowers for a long time, she might think that you have no feelings any more for her.
If you have already a girlfriend and you care about her you should show your feelings. If you decided to do this by bringing her flowers, you have a large variety to choose from. Every kind of flower has a particular language, all of them express something. So, according toyour feelings for her and what you want to show her, choose the flower which it represents you.