The Mugunghwa (Rose of Sharon, or hibiscus syriacus) has been an important flower in Korea for thousands of years. The Silla Kingdom (which ruled for almost 1000 years, until 935 AD), called itself the "Mugunghwa Country."
Today, the flower is mentioned in Korea's national anthem ("Mugunghwa samcheolli hwaryeo gangsan" or "Rose of Sharon, thousand miles of beautiful mountain and river land") and is found in other national emblems, like the Coat of Arms.
The government adopted the Rose of Sharon as an official symbol of Korea after the country was liberated from Japan. The Rose of Sharon has many characteristics that make it the perfect national flower for Korea. The flower blooms for a long time (from early July through late October) and there are thousands of blooms on each plant. It's a tough plant that can bloom in difficult situations; cut and placed in a vase, the flower lasts longer than many others. Korean word mugung means "immortal".
The strength and beauty of the flower represents the Korean people and the many trials they have overcome.