Full of symbolism, this plant has mystical roots by Michelle Gervais Fine Gardening issue Photo/Illustration: Michelle Gervais Shamrocks have been symbolic of many things over the years. According to legend, the shamrock was a sacred plant to the Druids of Ireland because its leaves formed a triad, and three was a mystical number in the Celtic religion, as in many others. St. Patrick used the shamrock in the 5th century to illustrate the doctrine of the Holy Trinity as he introduced Christianity to Ireland. "Wearin' o' the green" The shamrock became symbolic in other ways as time went on. In the 19th century it became a symbol of rebellion, and anyone wearing it risked death by hanging. It was this period that spawned the phrase "the wearin' o' the green". Today, the shamrock is the most recognized symbol of the Irish, especially on St. Patrick's Day, when all over the world, everyone is Irish for a day! The original Irish shamrock (traditionally spelled seamróg, which means "summer plant") is said by many authorities to be none other than white clover (Trifolium repens), a common lawn weed originally native to Ireland. It is a vigorous, rhizomatous, stem-rooting perennial with trifoliate leaves. Occasionally, a fourth leaflet will appear, making a "four-leaf clover," said to bring good luck to the person who discovers it. Grow your own shamrock Photo/Illustration: Michelle Gervais If you'd like to grow your own shamrock, you have a couple of options. You let the widely recognized white clover invade your lawn, or you can grow the Americanized version, Oxalis tetraphylla, the lucky clover. This is the plant you will usually find in gift shops in March. Oxalis tetraphylla is a tender perennial in most parts of this country, hardy only in USDA Hardiness Zones 8 to 9. For this reason it is usually grown as a house plant, with a winter dormancy period. It needs bright light to thrive, as well as moist, well drained soil. When the plant begins to go dormant for the winter, keep the soil barely moist, and resume regular watering in the spring when the plant puts out new growth. Did you like this article? Read a three-part account of culinary herbalist Susan Belsinger's visit to Ireland Cook a traditional Irish meal with a Top St. Patrick's Day Recipes  from our sister site FineCooking.com We have many more fun features on our site: • Readers' photo galleries • Botanical memory game • Blog by Fine Gardening editors • Dozens of videos on gardening • Fine Gardening's Garden Photo of the Day • Visit our sister site: VegetableGardener.com  View the discussion thread.