Merriam-Webster defines a shamrock as “a small plant with three leaves on each stem that is the national symbol of Ireland”—not to be confused with the lucky four-leaf clover.
The yellow-flowered Old World clover, according to the dictionary, is often regarded as the “true” shamrock.
History of the shamrock
Its history dates back to ancient Ireland when the shamrock, also called the “seamroy” by the Celts, represented the rebirth of spring.
During the 1798 Irish Rebellion when the English began to conquer Irish land and make laws against their language and practice of Catholicism, wearing the shamrock became a symbol of Irish nationalism, according to History.com.
But contrary to popular belief, Ireland’s national symbol isn’t the shamrock. It’s actually the harp, which you’ll find on Irish coins, state seals and the presidential flag.
And while green is the color most associated with Ireland today—arguably due to both the shamrock and Ireland’s lush nature—the national color of origin was actually a shade of blue used by the Order of St. Patrick, the patron saint of Ireland.
Why is the shamrock linked to St. Patrick’s Day?
According to St. Patrick's Day lore, St. Patrick used the leaves of a shamrock as a metaphor for the holy trinity. Each leaf represented either the Father, the Son or the Holy Spirit.
Many representations of St. Patrick depict the patron saint with shamrocks tied to his robes, the Sun reported.