Now's the time to be aware of the difference between the four-leaf clover and the three-leaf shamrock.
They are members of the same botanical family. Besides the shape, the difference is in their symbolic use. The four-leaf clover is considered lucky. As a child we would search masses of clover for one that had four leaves, press it and save it for good luck.
The three-leaf shamrock is a religious symbol. According to legend, when preaching to the pagans in Ireland, St. Patrick used the shamrock to illustrate the doctrine of the Holy Trinity. The belief that there are three persons in one God -- Father, Son and Holy Spirit. The shamrock plant in Ireland is considered a small clover.