Unlike most ornamental trees that bloom in spring, Hibiscus syriacus L. (Rose of Sharon), which is the national flower of Korea, has nearly 60 to 100 d of flowering time from early July to late October, and there are more than 350 varieties of this plant that have been developed worldwide (Ha et al., 2013; Lee, 2013). The varieties of H. syriacus are categorized into single or double flowers depending on the number of petals and depending on the color patterns on the petals. They are categorized as ‘Baedal’ (white petals), ‘Dansim’ (petal with red-eye zone), and ‘Asadal’ (red patterns on the edge of petals) (Korea Forest Service, 2008). The Rose of Sharon, which has red or white flower with five petals and a vivid red-eye zone in the center is a symbol of the Korean culture and was symbolically designated in the early 1990s by the Korea Forest Service (Song, 2004).
However, in Korea, the Rose of Sharon has a misinterpreted image of being easily infected with aphids but it is also recognized as a robust tree that can survive in poor soil conditions. It is also widely believed that the flowers are small and not beautiful because they are planted in raw land with poor management (Korea Forest Service, 2008). Moreover, most of the seedlings that are planted in Korea give rise to trees with an obscure origin; but when initially planted, they are managed with no knowledge of the characteristics. Therefore, until they mature and bloom, it is difficult to fully discover the excellence of the flowers (Korea Forest Service, 2008).
Since the 1970s, attempts have been made to develop new varieties with diverse characteristics to improve how the public perceives the Rose of Sharon and to increase the genetic diversity of the breeding groups through artificial interbreeding or by inducing mutations through radiation or chemicals (Ha et al., 2013; Kyung, 2001; Shim et al., 1993; Yu and Yeam, 1987). The National Institute of Forest Science (NIFoS) has been working continuously to enhance the beauty and excellence of this tree through artificial interbreeding, and recently NIFoS has developed more than 20 new varieties, such as H. syriacus ‘Sŏndŏk’, H. syriacus ‘Chilbo’, and H. syriacus ‘Kojumong’. They are also focusing on developing new types that are easier to grow instead of focusing on the color of the flower (Korea Forest Service, 2008).
As of 2010, local governments, public organizations, and schools of all levels in Korea have been increasingly demanding the development of gardens that include the Rose of Sharon trees and wanting to plant them as roadside trees to stimulate a sense of national pride (Kwon et al., 2012). This research developed a new cultivar to be planted as street trees. Furthermore, to meet these recent expectations of the Rose of Sharon, the new cultivar has a faster tree growth and is visually appealing because of its larger flowers with thicker red-eye zones.
KyungH.Y.2001Breeding of single and three way interspecific hybrids among Hibiscus syriacus interspecific hybrid (H. syriacus × H. paramutabilis) and H. sinosyriacus. Ph.D thesis Kangwon Univ. Korea
KwonH.Y.KimS.H.ParkH.S.2012Growing and management of Hibiscus syriacus the national flower of Korea. Korea Forest Research Institute (KFRI) Seoul Korea
KwonH.Y.KimS.H.ShimS.J.NamJ.I.2014The encyclopedia of the Rose of Sharon breed. Korea Forest Research Institute (KFRI) Seoul Korea
Korea Forest Service2008A master plan for more market-friendly and extensive utilization of the national flower. Daejeon Korea. p. 1–8.
LeeJ.S.2013Distribution and status of H. syriacus of the world. Proceedings of the 5th symposium of H. syriacus Research Society. Seoul Korea
LangenheimN.WhiteM.TapperN.LivesleyS.J.Ramirez-LoveringD.2020Right tree, right place, right time: A visual-functional design approach to select and place trees for optimal shade benefit to commuting pedestriansSustain Cities Soc.52101816doi: 10.1016/j.scs.2019.101816
Royal Horticultural Society Flower Council of Holland2001RHS color chart. 4th ed. London UK
SongW.S.2004Hibiscus syriacus—What are the characteristics of the flower? Semyeongseogwan Seoul Korea
YuT.Y.YeamD.Y.1987Korean national flower Hibiscus syriacus. Hakwon Co. Korea