Four-leaf clover

The four-leaf clover is a rare variation of the common three-leaf clover. According to tradition, such clovers bring good luck: In addition, each leaf is believed to represent something: the first is for faith, the second is for hope, the third is for love, and the fourth is for luck.

It has been estimated that there are approximately 10,000 three-leaf clovers for every four-leaf clover; even so, this probability has not deterred collectors who have reached records as high as 160,000 four-leaf clovers.

Clovers can have more than four leaves. Five-leaf clovers are less commonly found naturally than four-leaf clovers; however, they, too, have been successfully cultivated. Some four-leaf clover collectors, particularly in Ireland, regard the five-leaf clover, known as a rose clover, as a particular prize. In exceptionally rare cases, clovers are able to grow with six leaves and more in nature. The most leaves ever found on a single clover stem (Trifolium repens L.) is 56 and was discovered by Shigeo Obara of Hanamaki City, Iwate, Japan, on 10 May 2009.

It is debated whether the fourth leaf is caused genetically or environmentally. Its relative rarity (1 in 10,000 clovers) suggests a possible recessive gene appearing at a low frequency. Alternatively, four-leaf clovers could be caused by somatic mutation or a developmental error of environmental causes. They could also be caused by the interaction of several genes that happen to segregate in the individual plant. It is possible all four explanations could apply to individual cases. This means that multiple four-leaf clovers could be found in the same clover plant.

Researchers from the University of Georgia have reported finding the gene that turns ordinary three-leaf clovers into the coveted four-leaf types. Masked by the three-leaf gene and strongly influenced by environmental condition, molecular markers now make it possible to detect the presence of the gene for four-leaves and for breeders to work with it. The results of the study, which also located two other leaf traits in the white-clover genome, were reported in the July/August 2010 edition of Crop Science, published by the Crop Science Society of America.

The other leaf traits, the red fleck mark and red midrib, a herringbone pattern that runs down the center of each leaflet in a bold red color, were mapped to nearby locations, resolving a century-old question as to whether these leaf traits were controlled by one gene or two separate genes.

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Wikipedia