The shamrock is a symbol of Ireland. It is a three-leafed old white clover. It is sometimes of the variety Trifolium repens (a white clover, known in Irish as seamair bhán) but today usually Trifolium dubium (a lesser clover, Irish: seamair bhuí).
The diminutive version of the Irish word for “clover” (“seamair”) is “seamróg”, which was anglicised as “shamrock”, representing a close approximation of the original Irish pronunciation. However, other three-leafed plants — such as black medic (Medicago lupulina), red clover (Trifolium pratense), and wood-sorrels (genus Oxalis) — are sometimes designated as shamrocks. The shamrock was traditionally used for its medical properties and was a popular motif in Victorian times. It is also a common way to represent Saint Patrick’s Day.
The four-leaf clover is often confused with the shamrock. While the four-leaf clover is a symbol of good luck, the three-leafed shamrock is mainly an Irish Christian symbol of the Holy Trinity and has a different significance.