Hibiscus mutabilis, also known as confederate rose, cotton mallow or Dixie rose-mallow, is native to southeastern China (Flora of China Editorial Committee, 2006; Scheper, 2003; Welch, 2009). Hibiscus mutabilis is grown as an ornamental throughout the southeastern United States and is hardy in U.S. Department of Agriculture (USDA) zone 7 to 9 (Scheper, 2003). It is popular for its large, soft, gray-green foliage during the summer, and large, showy flowers produced late in the season when few other plants are in bloom (Blythe, 2012; Russ, 2007). Hibiscus moscheutos and closely associated species of section Trionum are native to the eastern half of the United States (Small, 2004). Hybrids of these American species are widely available because they are winter hardy in much of the eastern United States, have attractive, tropical-looking flowers in a range of bloom sizes from 5 to 30 cm in diameter, and flower from early summer through late fall (Malinowski et al., 2012). Examples of artificial hybridization between H. mutabilis (2n = 92) and the endemic North American species in Trionum section (2n = 38) such as Hibiscus coccineus and H. moscheutos have been reported, but the resulting F1 plants were seed sterile (Kuwada, 1961, 1962; Winters, 1970).
The goal of the hybridization efforts at the USDA-ARS Thad Cochran Southern Horticultural Laboratory in Poplarville, MS was to develop hibiscus cultivars with improved garden performance, reduced plant height, improved biotic and abiotic stress resistance, and prolific production of flowers of diverse colors. To that end, two Hibiscus species, H. moscheutos and H. mutabilis, were hybridized because hybridization among different species and genera is one of the most important breeding methods for improving ornamental plants (Kuligowska et al., 2016).
Three seedling selections, ‘Hapa White’, ‘Hapa Pink’, and ‘Hapa Red’, have been released from this research. These cultivars are interspecific hybrids with white, red, or pink flowers that thrive in diverse landscape environments. The three cultivars all bloom over an extended season as compared with the parental species. This extended flowering is due in part to the clones being sterile, setting neither seed nor seed pods. Growers who have evaluated the three releases report that overwintering losses are reduced and spring vigor is improved as compared with their traditional crops of H. mutabilis hybrids in the same environment.
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Kuligowska, K., Lutken, H., Christensen, B. & Muller, R. 2016 Interspecific hybridization among cultivars of hardy Hibiscus species section Muenchhusia Breed. Sci. 66 300 308
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Kuwada, H. 1962 The F1 hybrids obtained from Hibiscus mutabilis × H. coccineus (Studies on interspecific and intergeneric hybridization in the Malvaceae V) Tech. Bull. Fac. Agr. Kagawa Univ. 14 1 5
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