Shamrock

A shamrock is a young sprig of clover, used as a symbol of Christianity in Ireland. Saint Patrick, Ireland's patron saint, is said to have used it as a metaphor for the Christian Holy Trinity. The name shamrock comes from Irish seamróg, which is the diminutive of the Irish word for clover (seamair) and means simply "little clover" or "young clover".

Shamrock usually refers to either the species Trifolium dubium (lesser clover, Irish: seamair bhuí) or Trifolium repens (white clover, Irish: seamair bhán). However, other three-leaved plants—such as Medicago lupulina, Trifolium pratense, and Oxalis acetosella—are sometimes called shamrocks or clovers. The shamrock was traditionally used for its medicinal properties and was a popular motif in Victorian times.

https://en.wikipedia.org/wiki/Shamrock