Oakleaf Hydrangea (Hydrangea quercifolia Bartr.): Horticulture, Genetics, Breeding, and Conservation

Oakleaf hydrangea is a shrub that is native to the southeastern United States and is growing in popularity as an ornamental plant. Like other cultivated hydrangea species, oakleaf hydrangea has showy flowers but also has unique phenotypic characteristics that provide additional value as an ornamental shrub. Despite the enormous popularity of hydrangeas as garden plants, little research has been done on oakleaf hydrangea. This review synthesizes the existing oakleaf hydrangea literature and draws on work done in other Hydrangea species to bring attention to the current knowledge and identify gaps to be filled. After introducing the genus, the review focuses on the horticultural aspects of oak-leaf hydrangea, genetics and breeding of several selected traits, as well as the conservation concerns for the species. Finally, future lines of research that would provide valuable information for the breeding and conservation of oak-leaf hydrangea are suggested.