War of the Roses
The house of Lancaster uses Red Rose as their flower as you can see in the image on. As for The House of York they used the White Rose referred to as the Rose alba or rose argentwhich is also depicted in the same picture. The two houses fought in several battles between 1455 and 1485.
Henry VII introduced the Tudor rose in which he combined a red rose and a white rose to create. Henry Tudor defeated the last Yorkist king Richard III and married Edward IV's daughter Elizabeth of York to unite the two houses. The result was the Tudor rose (the Union rose) which you can see on your below. It’s the national flower of England.
https://ipfs.busy.org/ipfs/QmQCYWWHiwXvqUZVE8moD6NwqaFKyYtef1ZW9pz3tnUVUv
The Tudor rose appears of the uniforms of Queen's Body Guard of the Yeomen of the Guard are a bodyguard of the British Monarch.
https://ipfs.busy.org/ipfs/QmVXfjHdPnaibsdeSXDiFpkLzU891dgdckTsM2ueNW9j5J
The Tudor rose appears on The Arms of Canada, also known as the Royal Coat of Arms of Canada.
https://ipfs.busy.org/ipfs/QmXrw3xjGGm5afC82hqpATU71pEbuAuqLRs2zJLdewTpWn
The Tudor rose as it appears on Royal Badge of England.
https://ipfs.busy.org/ipfs/QmX5vuvLWQ8jrpT8fhrFtsKURn4KishVcNe4c4AuxgLDpw
The Union of the Crowns was symbolised in James Stuart VI/King James I's personal royal heraldic badge after 1603, the Tudor rose dimidiated with the Scottish thistle ensigned by the royal crown. - From Wikipedia