Flowers go into Advanced barter vallet, if you have bought it. If not, they go to the bags.
Yes, I know. But in order to get them into the barter wallet (if you have any), they need to be bound, that was my point. But having pondered my first post myself, I think (if I remember correctly) the flowers had been bound even before the introduction of that wallet. That would make my barter-wallet-theory obsolete anyway.
Another reason could be: If unbound, gamers would be able to collect huge amounts of them to sell on AH, even after the event (when there is no more flower-barterer).
But probably Ranilin is right
"Someday I'm going to move to Michel Delving
and leave all this behind". - (Hobbit in Waymeet)