Winter-hardy hibiscuses are herbaceous perennials that regenerate from root buds each spring in USDA hardiness zones 5 through 9. Colloquially known as Rose Mallows, the most recent taxonomic revision (Blanchard, 1976) recognizes five species (Hibiscus coccineus Walter, Hibiscus dasycalyx Blake & Shiller, Hibiscus grandiflorus Michaux, Hibiscus laevis Allioni, and Hibiscus moscheutos L.) that comprise the North American taxon Hibiscus L. sect. Muenchhusia (Heister ex Fabricium) O. Blanchard (Malvaceae) (Small, 2004). A number of additional taxa associated with H. moscheutos have been variously recognized historically as varieties, subspecies, or distinct species. Primary among these are Hibiscus moscheutos subsp. palustris L., native to the northeastern United States, and Hibiscus moscheutos subsp. incanus Wendl., indigenous to the southeastern coastal plain (Blanchard, 1976).
Native populations prefer wetland habitats such as flood plains but are tolerant to wide fluctuations in soil moisture. Rose mallows are long-day plants (Warner and Erwin, 2001) that flower from late spring through fall. Flowers last for a single day with color varying from scarlet rose in H. coccineus to white, lavender, and pink shades in the other four species. Studies of pollination in H. moscheutos indicate that the species is generally self-compatible but that the trait is variable with some lines rapidly develop inbreeding depression in progeny (Snow and Spira, 1993). The five species have a shared chromosome number of N =19, but artificial hybridization studies resulted in grouping the species into two groups based on seed set (Wise and Menzel, 1971). Hibiscus grandiorus and H. moscheutos (Group I) were entirely interfertile, and H. coccineus and H. laevis (Group II) were also interfertile, but crosses between groups produced few viable seed. Although Wise and Menzel (1971) did not include H. dasycalyx in their studies, subsequent work has shown that H. dasycalyx is closely related to H. laevis (Klips. 1995; Small, 2004) and clearly belongs in Group II.
Although breeding of rose mallows has focused on developing new clones with improved horticultural traits (Malinowski et al., 2012) such as branching and flower color, there is a need for clones with improved disease resistance, particularly in the southeastern United States. Both ‘Lufkin Red’ and ‘Lufkin White’ have desirable horticultural traits in combination with demonstrated high levels of field resistance to the leaf spot complex (Pirone, 1970) that is problematic on winter-hardy hibiscus clones in areas with warm nights and high humidity.
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