The English Rose

The rose became the floral symbol of England with the marriage in 1236 of Henry III and Eleanor of Provence, who was associated with the Golden Rose of Provence. From this rose was derived the red rose of the House of Lancaster and the white rose of the House of York, famous in the War of the Roses.

Eleanor later used the white rose as her emblem (Rosa alba), while her oldest son Edward I (reigned 1272-1307) adopted the Golden Rose (Rosa aurea) and her younger son Edmund, Earl of Lancaster adopted the red rose (Rosa gallica), although it's really pink...

The rose became the national flower of the United States in 1986.

For more on rose symbolism, here.