Nowadays, brides and their families are 'footing' the bill for the flowers, but alas, the groom has some 'pretty' responsibilities too. Many brides are simply not aware of this fact and others have decided that as a couple they are going to pool their funds and pay for all obligations (together). Still others have decided have varying members of the family pay for a service of their choosing and yet others have left everything to the bride.
In Western, Judea-Christian tradition, Emily Post has set the etiquette. And yes, the groom' family pays for the bride's bouquet. And how wonderful that is. The bride's bouquet is an accessory, floral jewelry, 'eye candy' and how much more special your bouquet becomes when you know that this was his gift to you.
Certainly that does not mean that he gets to pick out all your flowers. For some, that's a disastrous idea. But this prepares him for the future of sending you flowers and gifts for all those momentous occasions of life, the 'just because(s)', the cheer you up days and the 'let me out of the dog house days'.
In a synopsis the groom (groom's family) pays for:
The brides bouquet and going away corsage
Both sides of the family's corsages including all the mothers and grandmothers.
The boutonneires of the groom's attendants including groomsmen, ringbearer, and ushers.
Discuss this early with your families to avoid confusion closer to the wedding day when all the bills are due. This will lend to a mutual understanding between the families, less stress and resentment, better preparation and easier budgeting as you plan the day.