St. Patrick's Day falls on Thursday, March 17, 2022. In addition to leprechauns and pints of Guinness, four-leaf clovers have become an icon of the holiday. If you plan on celebrating Irish culture by searching for one in your backyard, prepare to be out there for a while; your chances of finding a four-leaf clover are one in thousands. But there are some steps you can take to increase your luck.
Appearing rarely in nature, it's easy to see how clovers sporting an extra leaf came to be viewed as lucky. The odds most commonly cited for finding one in the wild are about one in 10,000. According to Readers Digest, an independent survey of 5.7 million clovers conducted by researchers in Switzerland had a more encouraging conclusion. They observed one four-leaf clover for every 5076 three-leaf specimens in the study.
The rarity of this phenomenon has to do with genetics. Extra leaves in the common clover species white clover, or Trifolium repens, are the result of a mutation passed down through a recessive gene. Clover chromosomes come in packages of four instead of two, as is the case in humans, which means the chances of recessive traits coming through are even slimmer. Clovers only grow four leaves if they have the gene mutation on all four chromosomes. Even when the plant's genome is right, external factors like temperature and soil acidity influence whether that extra leaf will reveal itself at all.
The genetic nature of four-leaf clovers means that they aren't distributed evenly throughout the world's clover patches. They grow in clusters, so if you find one clover with four leaves, its relatives may be close by. An Australian woman experienced this trend firsthand when she discovered 21 four-leaf clovers in her front yard in 2014. So if you want to find a good-luck charm of your own, try searching in an area where you know a four-leaf clover was spotted recently.
Though the two terms are often confused, shamrocks and four-leaf clovers aren't the same thing. A shamrock is the three-leaf version of the plant, and according to legend, St. Patrick used one to illustrate the Holy Trinity. Here are more facts about St. Patrick's Day you should know.
[h/t Reader's Digest]