Each of the four nations of the UK has a floral emblem, worn on its patron saint’s day, and each comes with a legend of varying reliability.
England — the Tudor rose
Not simply a red rose. The Tudor rose is a white rose superimposed on a red one, and it is a piece of political branding nearly as effective as any modern logo.
The Wars of the Roses were fought between the House of Lancaster, whose badge was a red rose, and the House of York, whose badge was white. When Henry Tudor won at Bosworth in 1485 and married Elizabeth of York, he combined the two badges into one and used it everywhere — on buildings, coins, seals and liveries — as a constant visual argument that the conflict was over and the houses were united.
It is still used as the emblem of the England rugby team, on the uniforms of the Yeomen Warders, and on the twenty pence piece.
Scotland — the thistle
A spiky purple weed that Scotland adopted with some relish. The legend, first recorded much later than the events it describes, has a Norse raiding party creeping barefoot towards a sleeping Scottish camp by night. One of them trod on a thistle, cried out, and the alarm was raised.
It became the royal badge of Scotland in the fifteenth century, and gives its name to the Order of the Thistle, Scotland’s highest order of chivalry, whose motto is Nemo me impune lacessit — “no one provokes me with impunity”, or in the Scots version, “wha daur meddle wi me”.
Wales — the daffodil and the leek
Wales has two, and the older is the leek. Tradition holds that St David instructed Welsh soldiers to wear one in their caps to distinguish themselves from the Saxons in battle, and Shakespeare has Henry V refer to the custom. The Welsh Guards still wear a leek on St David’s Day, and a leek is eaten raw by the youngest soldier in the regiment.
The daffodil is a nineteenth-century arrival, and its rise is partly linguistic. The Welsh for leek is cenhinen, and for daffodil cenhinen Bedr — “Peter’s leek” — and the closeness of the words made the substitution easy. Lloyd George is often credited with promoting the daffodil, which has the practical advantage of being both prettier and less pungent to wear on a lapel.
Ireland — the shamrock
A three-leaved clover, said to have been used by St Patrick to explain the doctrine of the Trinity to pagan converts — three leaves, one stem. The story is not recorded until many centuries after Patrick, which has not affected its popularity.
It is worn on 17 March, and the Irish Guards are presented with shamrock by a member of the Royal Family each St Patrick’s Day, a tradition begun by Queen Victoria in 1900.
Note that the shamrock is not the four-leaf clover, which is simply a rare mutation and a luck charm with no national meaning at all.
Combined
Rose, thistle, shamrock and leek are frequently shown together on British coins, badges and public buildings as an emblem of the union — most visibly on the reverse of the pound coin designs, and around the base of the royal coat of arms in many carvings.