Shamrock is the English form of the Irish word seamrog which literally translated means 'little clover' or 'young clover' (the Irish word is a compound formed from seamair (= clover) and og (= young or small). Shamrock was first clearly used as a plant name by the English herbalist, John Gerard, in 1596 when he wrote that meadow trefoils are called Shamrockes.

There are many misconceptions and myths about shamrock. At its simplest a shamrock is exactly what the original Irish word indicates, and John Gerard stated - clover.

It must be stressed that there is no one plant, unique to Ireland, which alone bears the name shamrock. In 1988 a survey conducted at the National Botanic Gardens, Glasnevin, Dublin, during which wild-collected samples of shamrock from all over Ireland were scientifically studied, revealed that when Irish folk wear shamrock it can be one of four common clovers or trefoils. These are

lesser trefoil, seamair bhui - Trifolium dubium 46%

white clover, seamair bhan - Trifolium repens 35%

black medick, dumheidic - Medicago lupulina 7%

red clover, seamair dhearg - Trifolium pratense 4%

The proportions quoted for 1988 differ little from those recorded by a similar survey in 1893, so the our concept of a shamrock has not altered during the past century. Occasionally nowadays wood sorrel (Oxalis acetosella, in Irish seamsog) may be considered as shamrock but its claim to be the true shamrock was rejected as long ago as 1830!

In other words, native Irish folk do not agree on a single wild plant as the modern manifestation of the shamrock. They do agree that it is a smaller leaved trefoil - about St Patrick's Day both lesser trefoil (sometime called yellow clover) and white clover have compact shoots and small leaves.


It is frequently repeated that shamrock will not grow in any soil but Irish soil. This is nonsense. Each of the clovers worn as shamrock grows outside Ireland as a wild plant, in Britain, Europe, and farther afield too. You can collect shamrock anywhere, almost everywhere.

Shamrock seed is frequently sold in souvenir shops - it will be lesser clover, skilfully packaged and marketed to beguile. It will grow quickly and easily in any good garden loam or in any artificially-produced potting compost that contains lime. It does not need to be cultivated indoors; indeed it is best to grow it outside.

As a general rule, clovers do not flourish in acid, wet soils. Seed sown out-of-doors in late summer (August) will germinate and be ready to harvest on St Patrick's Day the following year. Seed sown in autumn (October) in a cold greenhouse will also be a suitable size for use too.

If left to grow, shamrock will take on the full characteristics of the parental clover, producing vigorous shoots, larger leaves and forming clumps up to half a metre across. They will bloom in summer with small yellow flowers (lesser clover, black medick), white flowers (white clover), crimson flowers (red clover). Furthermore they will become pestilential weeds if allowed to seed and spread - white clover will be the worst as it can spread rapidly by 'runners'.

Various peculiar variants of the clovers are treasured as garden plants. St Patrick's Tears was a name used last century for the purple- and multi-leafleted form of white clover (Trifolium repens 'Purpurascens Quadrifolium'). There is a more elegant (but equally weedy) golden veined red clover (Trifolium pratense 'Susan Smith').

If you would like to cultivate an elegant plant, shamrock-like, may I recommend Parochetus communis which has wonderful rich blue pea-like flowers. A native of the Himalaya, at least it belongs to the right family unlike wood sorrel and the various cultivated forms of Oxalis which are frequently called - incorrectly - shamrock. In America they are even marketed as shamrock. These can be equally weedy, particularly forms of Oxalis corniculata. They do make fine garden subjects, but if they set seed will become ineradicable weeds.

Don't say you were not warned!


There is no historical evidence that St Patrick had any connection with shamrock; nothing can be traced in historical documents to confirm the legend that he preached to the Irish people using a trefoil (three leaflets on one stalk) as a parable for the Holy Trinity (Three Persons in One God).

The story was first recorded in 1726 in a book about the wild flowers of Ireland written by an English dissenting (protestant) cleric, Dr Caleb Threlkeld, who recorded that

 This Plant [white clover] is worn by the People in their Hats upon the 17. Day of March yearly (which is called St. Patrick's Day.) it being a Current Tradition, that by this Three Leafed Grass, he emblematically set forth to them the Mystery of the Holy Trinity.


Shamrock is not an official emblem in the Republic of Ireland - the state emblem is the 12-stringed harp and this is embossed on official government documents and is on the presidential standard. However the green trefoil is registered under international trade-mark conventions as a symbol of Ireland. Shamrocks do not appear on Irish coins, bank-notes or postage stamps, as a rule.

Shamrock does appear in the Royal arms of the United Kingdom of Great Britain and Northern Ireland, representing Northern Ireland, alongside the floral emblems of England (rose), Scotland (thistle) and Wales (daffodil). Shamrocks has also featured on coins and stamps of the United Kingdom.

Unofficially, however, the shamrock - or rather a green trefoil - is universally recognized as a badge of the Irish; it is used on aircraft, ships, clothes, books, and all sorts of bric-a-brac. And of course shamrock is worn on St Patrick's Day.


The custom of wearing shamrock seems to date from the late 1600s. In a verse published in 1689 there is a reference to this practice. At the same period, and indeed into this century, crosses of ribbons were worn in honour of our patron saint.

In bygone days it was normal to wear shamrock in your hat, not on your breast. A famous painting by Sir Joshua Reynolds shows Lord Charlemont with a clump of shamrock in his hat, and when he paid a visit to Ireland in 1820, King George IV entered Dublin standing in his carriage, pointing ostentatiously to a large sprig adorning his hat.

In 1900 Queen Victoria instructed that all Irish soldiers serving in British regiments should wear shamrock on St Patrick's Day in memory of those who died during the Boer War. This practice continues today, although the reason is not remembered.


The festivities associated with St Patrick's Day frequently include convivial drinking - this has been so for many, many decades. Dr Threlkeld frowned upon the 'drowning' of the shamrock in 1726, and undoubtedly it was a much-loved custom then.


It was fashionable from about 1800 onwards to use shamrock as a decorative motive on buildings - even churches - lamp-posts, furniture, even on clothes, but the great 'explosion' in their use was after 1820 when almost anything of Irish connection had trefoils on them. Nowadays, we are more restrained, and shamrock are usually confined to souvenirs.

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© E. Charles Nelson, 7 March 2006

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