Four-leaf clover
A rare clover with four leaflets, kept as a sign of luck since at least the seventeenth century.
Also: lucky clover, shamrock, trefoil
White clover normally has three leaflets, and a plant with four turns up rarely, which is why finding one is taken as luck. An English text of 1620 says that a four-leaf clover helps the finder see fairies, and folklore says that Eve took one from Eden. The claim that ancient Druids prized it is popular but not documented. The three-leaf shamrock is a separate emblem of Ireland, tied to St Patrick, who is said to have used it to explain the Trinity. Some people say each leaf stands for faith, hope, love and luck. Four-leaf clovers are pressed, framed and sold, and plant geneticists have found that the extra leaflet can be inherited.