CARROLLTON, Mo. – If a leprechaun leaps from the faerie den this St. Patrick’s Day to ask if you know a shamrock from a clover, what will you answer?

“If you said the shamrock is a clover, you’re in luck,” says University of Missouri Extension field horticulturist Kathi Mecham.

In short, all shamrocks are clovers, but not all clovers are shamrocks.

The word shamrock comes from the Gaelic word semróg, which translates to “little clover.” Shamrocks are the most common and recognizable symbols of Ireland.

While a shamrock is a clover with three leaflets, some clovers have four leaves and are thought to bring luck to anyone who finds one. “There is about a 1 in 10,000 chance of finding a four-leaf clover,” says Mecham. As an Irish proverb says, “A good friend is like a four-leaf clover: hard to find and lucky to have.” Even rarer is the five-leaf clover.

By most accounts, the original shamrock is thought to be either yellow clover (Trifolium dubium) or white clover (Trifolium repens). Both plants have three oval green leaflets with tiny, ball-shaped floral clusters.

Clover draws bees, butterflies and other pollinators to the nectar of its lightly scented flowers.

“The shamrock has long been a part of Irish history and culture,” says Mecham. Legend has it that the Emerald Isle’s patron saint, Patrick, used the three-leaf clover to teach about the Holy Trinity of Christianity: Father, Son and Holy Ghost.

As St. Patrick’s Day approaches, grocery stores or floral shops will sell an attractive “shamrock plant.” This imposter is a plant from the genus Oxalis, a member of the wood sorrel family. It hails from mountainous regions of South and Central America, not Ireland.

Oxalis triangularis looks like clover with its three triangular leaflets. This eye-catching plant produces small white to pink flowers. Its leaves may be green, variegated or deep maroon.

While true shamrock has a fibrous root system, many oxalis species produce tubers, or bulb-like structures, says David Trinklein, MU Extension state horticulturist. “In fact, the plump, juicy tubers of Oxalis tuberosa have long been cultivated as a food source in Colombia and other South American countries. Referred to as oca by people indigenous to the area, it is second only to potato in acreage planted in the Central Andean region.”

Shamrocks prefer a porous medium that is barely moist. Fertilize only when growing. Place in indirect bright light to keep plants from becoming leggy. However, too much sun scorches the tender leaves.

Oxalis’ leaves begin to decline after a few months. Don’t despair, says Mecham. Your plant just needs a rest. When leaves start to die back, stop watering and allow leaves to dry. Remove the dead leaves and put the plant in a cool, dark spot for 2-3 months. Purple-leaf plants only need about a month’s dormancy. After the rest period, move the plant back to a window and begin watering again.

The leaves of oxalis and other shamrock plants fold up at night and reopen in the morning light, giving a wee “top o’ the morning” tip of the hat to its owner.

“With the right care, this attractive houseplant can be enjoyed for years,” says Mecham.

For more history of the oxalis, see “Oxalis: Shamrock’s Imposter” at https://ipm.missouri.edu/meg/2019/3/oxalis/.

Learn more about another favorite Irish plant, Bells of Ireland, at https://extension.missouri.edu/news/bells-of-ireland-a-st-patricks-day-favorite.

Photos

https://extension.missouri.edu/sites/default/files/legacy_media/wysiwyg/Extensiondata/NewsAdmin/Photos/Trif_dubium204ss.JPG
True shamrock: Yellow-flowered clover (Trifolium dubium). Photo by Krzysztof Ziarnek.

https://extension.missouri.edu/sites/default/files/legacy_media/wysiwyg/Extensiondata/NewsAdmin/Photos/2016/IMG_1308.JPG
Some plants sold as “lucky shamrocks” are wood sorrels, not true shamrocks. Photo by Michele Warmund, MU Extension.