Shamrocks, four-leaf clovers, wood sorrels and a few other similar plant species are often in the limelight in the spring and around St. Patrick’s Day, but which is which? They are often confused as the same plants even though each has its own attributes and only a few have associated folklore.
Shamrocks are a symbol of Ireland and St. Patrick’s Day. Shamrocks have three leaves that traditionally represent faith, hope and love. St. Patrick is believed to have used the three leaves of the shamrock to also represent the Holy Trinity in his religious teachings.
Plantwise, the shamrock is a clover. The Gaelic word from which shamrock is derived translates to “little clover” and the most likely candidates are lesser clover (Trifolium dubium) or white clover (Trifolium repens).
Lesser clover is a low-growing annual that is native to Ireland and common in grassy areas there. The plant has sprawling stems with delicate clusters of leaves in groups of three and small yellow flowers that look like a ball of tiny elongated petals. It is sometimes called lesser trefoil or yellow clover but is different than the plant referred to as yellow clover in the Midwest.
White clover has a similar growth habit but is perennial. Its leaves and flowers are a little larger than those of lesser clover with white flowers that are a little less than the diameter of a dime. It is common in lawns, parks and other grassy areas. White clover is sometimes thought of as a weed, but it is also an important forage crop and cover crop. Like other clovers, white clover fixes nitrogen (pulls it from the atmosphere and puts it back into the soil). It is also known as ladino clover or Dutch clover.
Four-leaf clovers are a naturally occurring mutation of clover commonly found in white clover. The rate of frequency of four-leaf clovers is reported to be between 1 in 5000 to 1 in 10,000 plants. However, some people have better eyes than others for such things and thus better luck in finding them. Or perhaps the luck of finding one leads to finding more, as the fourth leaf represents luck in folklore.
The youth program 4-H uses the four-leaf clover as its official emblem. For that program, the leaves represent the four H’s: head, heart, hands and health.
The indoor plants referred to as shamrocks or lucky clovers are various species of wood sorrel (Oxalis). They are related to clover and are also trifoliate, but wood sorrel leaves are heart-shaped with a fold down the middle. The plant may have gained popularity around the St. Patrick’s Day holiday because it blooms around that time as well as being similar in appearance to clover.
Another plant occasionally confused with shamrocks and clover is black medick (Medicago lupulina). Black medick is a type of clover that is related to alfalfa and is common in lawns and grassy areas. It has clover-like leaves in groups of three, but is much taller (2 to 3 feet at maturity if left to grow) and has very small yellow flowers. In mowed areas, stems may creep along the ground.
In a survey of Irish people, about 80 percent believed that either lesser clover or white clover was the true clover represented by the shamrock. The remainder of the population was divided between other clovers, wood sorrels and black medick, but the true shamrock always has three leaves.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.