The majority of the flowers were included in the bride and/or her family's bundle of costs—those for the ceremony, reception, bridesmaids, and flower girls. The groom and/or his family would historically buy the bride's bouquet, and all of the boutonnieres and corsages for appropriate wedding party and family members.
Being asked to be the bride's maid of honor is the kind of question that warrants a glass of champagne and a giant pat on the back! You're about to transform from friend or family member into the bride's right hand gal pal, her on-call therapist, her party planner, and — above anything else — her dose of reality when all the wedding stress seems to get out of hand.
The groom is traditionally expected to pay for the marriage license and officiant's fees, and buy the bouquet for his "date" (the bride), as well as her engagement and wedding rings and a gift; he should also purchase boutonnieres and gifts for his groomsmen.
Preparations have ben done at this point and I don’t tend to ask them to stage any of the getting ready list (often photographers will ask the groom to show his cufflinks or get the best man to hold up the rings, but it’s not really my style so I tend not to start the day by making them do this).