Rosa Mundi.

An early  legend says that ‘Rosa Mundi’ was named after Rosa­mund Clifford, the mistress of King Henry II who reigned as England’s monarch from 1154 to 1189.
Rosamund Clifford (1150-1176), also known as the "The Fair Rosamund" or "Rose of the World", was the long-time mistress of King Henry II. Henry was forced to marry Princess Eleanor who, jealous of her husband's relationship with the fair Rosamund, is said to have had her murdered by poison.
.After her death, Henry and Rosamund's family paid for a tomb at Godstow Nunnery near Oxford and put an endowment in place for it to be attended by nuns who were instructed to place Rosa Mundi flowers upon it on the anniversary of her death.