Why is rose the national flower of US?

Answer 1

In 1986, the US Congress passed an act declaring the Rose to be the "floral symbol" of the US. The following is a quote from President Regan at the signing of this act:

Americans have always loved the flowers with which God decorates our land. More often than any other flower, we hold the rose dear as the symbol of life and love and devotion, of beauty and eternity. For the love of man and woman, for the love of mankind and God, for the love of country, Americans who would speak the language of the heart do so with a rose.