These bags only hold items conceptually related to plants, like Un'Goro Soil and Herbalism supplies, but are larger than the average general bag. Only 1 herb bag may fill a slot in a bank at any time.
“Herb bags are a specific type of bag that allows the storage of herbs gathered by characters of...Herb bag
“Emerald BagItem Level 80Disenchants into: Not disenchantableBinds when equipped32 Slot Herb...Emerald Bag
“Satchel of CenariusItem Level 65Disenchants into: Not disenchantableBinds when equipped24 Slot...Satchel of Cenarius
“Hyjal Expedition Bag is a bag that will hold herbs and various other herb related drops/items...Hyjal Expedition Bag
“The Herb Pouch is a herb bag that will only hold herbs and nothing else in it. Unlike the other...Herb Pouch
“Cenarion Herb BagItem Level 55Disenchants into: Not disenchantableBinds when equipped20 Slot...Cenarion Herb Bag