“The luck of the Irish” has been a saying tossed around for decades, along with images of tiny green men, green beer and, of course, the four-leaf clover.

Most children have spent many a sunny afternoon searching for that one special clover to press in between the pages of a favorite book and wish upon their whole lives through. But it’s not an easy task actually finding a four-leaf clover, considering on average there are 10,000 three-leaf clovers for every true four-leaf one.

So just how did the four-leaf clover become synonymous with St. Patrick’s Day and Irish luck?

The four-leaf clover actually dates back to before Christianity to the Pagan period, when four-leaf clovers were widely considered Celtic charms. Celtic dominance once extended across Ireland, and it was originally the Druids (otherwise known as Celtic priests) who ascertained that the four-leaf clover was potent against malevolent spirits, thus thrusting its status as a good luck charm into mainstream society.

According to landscaping.about.com the leaves of a four-leaf clover are sometimes said to stand for faith, hope, love and luck. But another widely known interpretation comes in the form of an old song:

“I’m looking over a four-leaf clover that I overlooked before. One leaf is sunshine, the second is rain, third are the roses that grow in the lane. No need explaining the one remaining is somebody I adore. I’m looking over a four-leaf clover that I overlooked before.”

Clovers are difficult to grow indoors, but they make an excellent ground cover. One of the major pluses of using clover in the lawn is that it is unaffected by dog urine.

No ‘real McCoy’ shamrock

The other popular plant that is instantly recognizable as one of Ireland’s emblems is the shamrock. The term “shamrock” derives from the Gaelic word “seamrog,” which translates to “little clover.”

Leaves of a four-leaf clover are said to stand for faith, hope, love and luck, according to landscaping.about.com

This is quite vague considering how many kinds of clover there are. Consequently, a number of plants serve as Irish shamrocks during St. Patrick’s Day, but there is no “real McCoy” shamrock.

When the Irish wear the shamrock, it can be one of four varieties discovered by botanist Nathaniel Colgan, who endeavored to identify “the real shamrock” at the turn of the 20th century. He requested that people from all over Ireland send him living, rooted specimens. He then planted and labeled them all, and when they finally matured and blossomed he was able to determine four distinct varieties.

Three of the varieties are clovers, while the fourth is a clover-like plant known as “medick.” All four selections are in the pea family. They are: lesser trefoil or hopclover, white clover, black medick and red clover.

Various members of the wood sorrel family also are sold as shamrocks. These clover look-alikes grow more easily indoors, which makes them popular for interior design around St. Patrick’s Day. Wood sorrels are not related to any of the four varieties discovered by Nathaniel Colgan.

So how can all of these be considered Irish shamrocks?

Medicks, wood sorrels (also known as oxalis) and true clovers all have in common a trifoliate leaf structure, which is a compound leaf with three leaflets. The leaves fold up at night or on an overcast day and open in the daylight. By definition, an Irish shamrock has three leaflets; therefore, a four-leaf clover cannot technically be considered a shamrock.

Three is a significant number for Christians because of the holy trinity. Legend has it that St. Patrick used a three-leaf clover as an example to illustrate the trinity. This may or may not have occurred; it was never written down by St. Patrick himself in any of his journals. However, early Christian teachers most likely used the shamrock to illustrate the trinity.

Storebought shamrocks

Shamrocks available in floral shops and grocery stores are species of oxalis or wood sorrel. Oxalis leaves are clover-shaped and can be shades of green, red, purple or a combination of these colors. Oxalis blooms are white, yellow, pink or red depending on the species. There are hundreds of species, but the two that are commonly grown indoors are the Irish shamrock (oxalis acetosella) and the good-luck plant (oxalis deppei). Both have green leaves and petite white or red blooms. The good-luck plant has a white streak on its leaves.

Shamrocks are bulbs which are best planted close the surface in a peat-based potting soil. Feed them once a month. They grow well when potted alone among other shamrocks. They may have a period where they appear droopy or even dead, but they are just resting. During that period, don’t water them and relocate the plant to a dark place for their dormant period. Dormancy may last 2 to 3 months.

So get out there and capture a little luck of the Irish in the form a plant, who knows it may be more effective than wishing on a star.

Sources: Iowa State University Extension, www.irishcultureandcustoms.com, landscaping.about.com