Shamrock

Shamrock (Irish Seamrog, ”little clover”), common name for any of several trifoliate clovers native to Ireland (see Clover). The shamrock was originally chosen as the national emblem of Ireland because of the legend that Saint Patrick used the plant to illustrate the doctrine of the Trinity. Most shamrocks, particularly the small-leaved white clover, have been considered by the Irish as good-luck symbols since earliest times, and this superstition has persisted in modern times among people of many nationalities. Shamrocks or various representations of the plant are worn by celebrants on Saint Patrick's Day, March 17 of each year. The hop clover is widely accepted as the original shamrock picked by Saint Patrick.

Scientific classification: Shamrocks belong to the subfamily Papilionoideae, family Fabaceae (formerly Leguminosae). The white clover is classified as Trifolium repens and the hop clover as Medicago lupulina.