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Shamrocks, four leaved clovers and oxalis

President Obama accepts shamrocks from the Irish Prime Minister.
President Obama accepts shamrocks from the Irish Prime Minister.
White House photo

If you are traveling through the stores just before St. Patrick’s Day you are almost certain to find potted plants of “shamrocks” for sale. Some may have 3 leaflets, others four. Most are purple with pretty pink flowers. These are actually Oxalis and while they make pretty houseplants they are not the true shamrock of Irish legend. See how to care for them at the end of this article.

In Irish culture true shamrocks are worn in the labels of coats or on the hat on St Paddy’s Day through the drinking and parades and put into the last drink of the day, there is a toast, the drink is downed and the shamrock thrown over the left shoulder for luck. This is called drowning the shamrock. Others believe that the shamrocks three leaves were taught by St. Patrick to be symbols of the Holy Trinity although there is no proof that he ever used them to illustrate a sermon.

Since 1952 it has been a tradition for the Irish Prime Minister to present the President of the United States with a bowl of shamrocks in a fancy Waterford crystal bowl on St. Patrick’s Day. Unfortunately security protocol demands that the shamrocks be destroyed immediately after the ceremony and photo taking. The crystal bowls have various fates- President Reagan used one for jelly beans.

The shamrock also appears on Montreal, Canada’s flag as a symbol of one of the four major ethic groups which made up the city’s population when it was founded. It’s hard to think of Montreal as being part Irish. Almost everywhere the shamrock is seen as a symbol of good luck. Shamrocks usually have 3 leaflets, although they are sometimes portrayed with 4 leaflets.

But what plant family do true shamrocks belong to? In the late 1800’s a debate raged among botanists in Europe and the US over this very important question. Some believed firmly that shamrocks were wood sorrel or Oxalis and others that they were of the clover or Trifolium family. Both plants grow well in Ireland. A clever botanist by the name of Nathaniel Colgan carried out a survey in 1893 by asking residents of Ireland to send him pressed samples of the plant they considered a shamrock. The survey found that the Irish overwhelmingly chose a clover, either Trifolium dubium (Lesser or Hops clover) or Trifolium repens (White Clover) although a few wood sorrel leaves arrived also.

So what about that 4 leaved shamrock?

So what about 4-leaf clovers being a symbol of good luck? (Actually we should say 4 lobed clover leaf as the 4 parts are actually leaflets or sections of one leaf.) If you ever need to keep a bunch of kids occupied for a while tell them a 4 leaf clover is good luck and send them to look for one on the nearest patch of ground . If there is any clover nearby- either white or red clover- they may actually find one, although the odds are about 1 in 10,000 leaves. Some adults search diligently for four leaved clovers too, and some make a hobby of collecting them. The largest collection of 4 leaf clovers as of 2007 was that of Edward Martin Sr. from Cooper Landing, Alaska, with 111,060 four-leaf clovers. Clover can also have more than 4 leaflets. The largest number of leaflets on a clover leaf ever found was 56.

The clover leaf with 4 leaflets instead of 3 is a rather common mutation and it can be inherited. In fact there are varieties of white clover that have been developed that will have a high proportion of leaves with 4 or more leaflets. These are grown to make those lucky charms with a real 4 leafed clover inside. There is a purple leaved variety, T. repens 'Purpurascens Quadrifolium' and a green-leaved variety called T. repens 'Quadrifolium'.

Several white clovers have actually been developed as ornamental groundcovers, although they don’t seem to have caught on well, probably because clover has a tendency to become invasive. Four white clover cultivars, Frosty Morning, Patchwork Quilt, Irish Mist and Pistachio Ice Cream were developed at The University of Georgia and released in 2008. The clovers Dragons Blood, (a spot of crimson on each leaf) and Dark Dancer (dark purple) have been on the market for a while. White clover is considered to be an annual or short lived perennial but it reseeds itself easily. The above are all clovers with 3 leaflets.

Another clover that’s been adapted for ornamental use is being widely featured in garden catalogs this spring. Its Trifolium rubens, variety “Red Feather”. The familiar clover leaves are fuzzy silvery green and the plant puts out flowers on tall stems about a foot high that begin as silver buds and end as long lasting crimson flowers. The flowers are very attractive to butterflies and bees as well as to the eye. Grow in full sun to partial shade. The plant is hardy to at least zone 5.

What about caring for that Shamrock houseplant?

Those pretty shamrocks purchased in stores for Saint Patrick’s Day can make a great houseplant. Usually they have purple leaves with pink flowers although there are other colors. “Iron Cross” (Oxalis tetraphylla) is a four leaved oxalis, green with purple cross markings and pink flowers. Oxalis vulcanicola- “Molten Lava” has orange foliage with yellow flowers. Oxalis adenophylla “Silver Shamrock” has silver gray foliage with light pink flowers. It’s said to be hardy to zone 6. There are other varieties for plant collectors too.

While wood sorrel ( oxalis) species are common throughout most of the world the species used as “shamrocks” are usually tender perennials, and won’t survive outside in a cold winter. Keep them in a bright window and keep moist but not over watered to the soggy point. A light fertilization once a month with a fertilizer for flowering plants will keep oxalis blooming for long periods of time, although they will take occasional breaks from blooming. Well cared for plants will become larger and live for several years. The tender Oxalis can make great container plants outside during the frost free months.

Here are some additional articles you may want to read.

Read about an edible oxalis- Oca

Is everything in your garden legal?

How to grow the deadly beauties

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