The national flower of England is the rose. The flower has been adopted as England’s emblem since the time of the Wars of the Roses – civil wars (1455 – 1485) between the royal house of Lancaster (whose emblem was a red rose) and the royal house of York (whose emblem was a white rose). The Yorkist regime ended with the defeat of King Richard III by the future King Henry VII at Bosworth on August 22, 1485. Henry VII united the two roses into the Tudor rose (a red rose with a white center) when he married Elizabeth of York.

The national flower of Northern Ireland is the shamrock, a three-leafed plant similar to clover that is said to have been used by St Patrick to illustrate the doctrine of the Holy Trinity.

The motif of the linen or flax plant has also been adopted by Northern Ireland. Six flowers signify the six counties which make up Northern Ireland, while the plant itself is a reminder of the history and importance of linen in Northern Ireland's agriculture and manufacturing industries.

The Scottish national flower is the thistle, a prickly-leafed purple flower that was first used in the 15th century as a symbol of defence.

The three plants – the rose, thistle and shamrock – are often displayed beneath the shield of the Royal Coat of Arms.

The national flower of Wales is usually considered to be the daffodil, which is traditionally worn on St. David’s Day. However, the leek is also considered to be a traditional emblem of Wales, possibly because its colours, white over green, echo the ancient Welsh standard.