The genus Rosa is more commonly known as Rose. Roses are deciduous or semi-evergreen, perennial flowering plants. There are over a hundred species and thousands of cultivars. They can be erect shrubs, climbing or trailing, with stems that often have thorns. Flowers vary in size and shape and are usually large and showy, in colours ranging from white, yellow, red, pink to purple. They are often followed by red or purple fruits known as 'hips'. Most species are native to Asia, with smaller numbers native to Europe, North America, and northwestern Africa. Species, cultivars and hybrids are grown in gardens for their beauty and are often fragrant. Rose plants range in size from compact, miniature roses, to climbers that can reach 7 metres in height. Different species hybridize easily, and this feature has been used in the development of the wide range of garden roses. Most rose cultivars are made by rooting cuttings or by grafting or budding the desired cultivar onto a suitable rootstock. The rose is the national flower of the USA. During the 15th Century, the rose was used as a symbol for the factions fighting to control England. The white rose symbolized York, and the red rose symbolized Lancaster – as a result, the conflict became known as the "War of the Roses".