The Four-Leaf Clover: Leprechaun Luck or Genetics?

Sir John Melton once said, “If a man walking in the fields finds any four-leaved grass, he shall, in a small while after, find some good thing.” With St. Patrick's Day, millions of people around the world are going to be looking for their own lucky four-leaf clover. But what makes the four-leaf clover so lucky and rare to find? The answer lies in genetics! Most clovers have three leaves, with their scientific name being the genus Trifolium – that's Latin for three leaves. However, people have discovered that some clovers have four leaves, rather than three. While these four-leaf clovers do exist, they are extremely unique and difficult to discover. Why is this the case?

Traditionally, the original three-leaf clover has symbolized faith, hope, and love. In the Christian faith, the three-leaf clover also symbolizes the Father, Son, and Holy Spirit. This is because according to Christian beliefs, Saint Patrick used a shamrock to explain the Holy Trinity to a group of Irish people looking to convert to Christianity. However, the significance of the four-leaf clover is much different. Four-leaf clovers were Celtic charms thought to allow people to see fairies and to offer magical protection. In addition, they were also thought to ward off bad luck. As time passed, the four-leaf clover eventually came to symbolize good luck, rather than warding off bad luck. The legends say that the rare four-leafed clover is where we get our luck from. Don’t thank the leprechaun for this luck, however - thank genetic mutation. The four-leaf clover originates from a genetic mutation in the original three-leaf clover that caused it to have an extra leaf.

According to Wayne Parrott, a professor of crop sciences in the University of Georgia’s College of Agricultural and Environmental Sciences in Athens, the clover’s lucky fourth leaf sprouts from a mutation in the DNA of the genus Trifolium. The type of clover most associated with the four-leaf clover is the white clover. Parrott researched the DNA of this white clover and discovered which genes influence the shape and color of the leaves of the clover. He discovered that the white clover was an allotetraploid - which can be broken down into ploid, meaning chromosome, and tetra which means four. This discovery showed researchers that the white clover chromosomes each come from a different species, making this white clover the perfect breed of clover to study in order to understand the science behind the legend. In Parrott’s study, he grew 178 white clover plants and recorded any plant that had at least one four-leafed stem. The results of the study showed that four-leafed stems tended to favor warmer conditions - proving to Parrott and his team of researchers that the original three-leaved genome was likely an adaptation of the four-leaf clover for colder climates. The clover plant originates from the bean plant which has a lot of leaves, thus further validating the results of his study. Since the three-leaf clover made the clover more likely to survive, it is today the most prominent type of clover in the world. However, as DNA replicates, mutations occur, and every once in a while, there is a mutation that weakens the plant's ability to mask the four-leaf gene, allowing for us to find an occasional four-leaf clover. However, this mutation does not often occur, explaining why it is so rare and lucky. 

Now you know the significance of the four-leaf clover, and how it differs from the three-leaf clover. You also know about the fascinating genetics behind its odd occurrences in nature. So exactly how likely are you to find one of these lucky plants? Scientists say that for every 10,000 clovers, one of them will have four leaves. That’s about a .01% chance of finding a four-leafed clover. So, next time you find a four-leaf clover, thank genetics for the luck it brings!