I say the most beautiful flower on earth is the iris. It's scent and colors and poise are not to be beat. Best of all, the flowers come up year after year without any fuss. My irises have been gracing the south side of my house for more than 30 years; we don't really know when they were planted.
When the irises are in bloom, I spend every evening I can reading in the backyard. There is a two-day window where my lilacs are still blooming on one side of my lawn chair and the first irises are popping on the other. 7 p.m., you will find me there. Heaven.