Perhaps in part to its widespread use in St. Patrick’s Day decorations and imagery, the shamrock is widely considered the official symbol of Ireland. But while St. Patrick is believed to have used the shamrock to teach the Christian notion of the Holy Trinity, the clover was never an official symbol of Ireland. That designation is held by the harp, which has been featured on the coat of arms of Ireland for centuries. The harp also was adopted as the emblem of the Irish Free State when it separated from the United Kingdom in 1922.