A Florist is an NPC vendor that sell decorative flowers and bouquets to carry in the off-hand. They often sell other botanically related items. There are currently six in WoW, but effectively five vending sites, because the two florists in Stormwind are right near each other in the same room.
-  <Herbalism Supplies> on the Middle Rise of Thunder Bluff
-  <Florist> in Festival Lane in Old Stratholme
-  <Innkeeper> in the Inn at Valgarde in Howling Fjord serves a dual role as an innkeeper and a florist
-  <Flower Vendor> in Runeweaver Square in Dalaran