Sakura catches the Flower card in the second volume of the manga. There is an athletics day at Sakura's school! During the festivities, Sakura's father and Tomoyo's mother compete against each other in the parents race. All of a sudden, lots and lots of flowers rain down from the sky, buring the athletic field! Fujitaka and Sonomi are so involved in their race that they continue to run, even though the flowers are up to their waists! Touya and Yukito have to hold the finish line for Chiharu and Naoko because the flowers are almost over their heads! Sakura and Tomoyo fly above the school to see what is going on, and they see Flower dancing and throwing lots of flowers everywhere! Sakura and Tomoyo call Kero-chan to ask his advice, and he tells them that Flower loves parties, and she was probably just mad that she wasn't invited! After a cute dance with Flower, Sakura caught the card! Basically the same thing happened in the anime.
Flower is a very very sweet card!! She is also really beautiful! She can make any flower appear. This is a great card, but it is kind of hard to say if she is offensive, or defensive. Sakura has used her just to be sweet, and as a distraction during battles.
Go to the Flower Gallery!