Plant cure (Garden of Tranquillity)

Plant cure is used in the quest Garden of Tranquillity. You use it with some Rune dust to make a strengthened plant cure for the Burthorpe Vines. To make rune dust, you must use either Rune essence or Pure essence on an anvil, resulting in Rune shards. Afterwards, left-click it to grind it. After the quest you can make as much as you want, but it has no use.