|MadSci Network: Botany|
This is a good question for Saint Patrick's Day. The Irish shamrock is thought by many authorities to be white clover (Trifolium repens), which has mostly leaves with three leaflets. Botanically, a four leaf clover is actually a four leaflet clover because it is a single leaf with four leaflets. Several companies sell four leaf clovers as lucky charms or cover them with gold to make jewelry. Park Seed Company sells plants of a Red Four-Leaf Clover (Triflorum repens 'Atropurpureum'). Another company sells seeds of a four leaf clover with up to 39% of the leaves with four leaflets. A four leaf clover is a natural mutation. It occurs rarely enough that finding one is considered good luck. By selection and breeding, clover plants have been obtained that produce a high percentage of four leaf clovers. The same could probably be done for five leaf clovers, if they were commercially valuable. A company that sells four leaf clovers claims that it has plants that produce occasional four and five leaf clovers. Five leaf clovers are rarer than four leaf ones but not that rare. I'm not sure anyone has measured the percentage of four or five leaf clovers under natural conditions. If you had the time and patience, you could count how many three leaf clovers you have for every four or five leaf clover. References: White Clover White Clover Photos
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