Production of interspecific hybrid plants between Hydrangea scandens subsp. chinensis and Hydrangea macrophylla via ovule culture^©

BACKGROUND
McClintock systematically described the genus Hydrangea (McClintock, 1957). She included 23 species with a disjunctive distribution in both eastern Asia, eastern North America, and South America. Hydrangea macrophylla (Thunb. Ex J.A. Murr.)Ser. is the most popular of the species, and it is one of the most commercially important flowering shrubs in the world.
Hydrangea macrophylla native to Japan and China was cultivated in Japan long before introduction into Europe in the 1800s (McClintock, 1957; Wilson, 1923). For this species, numerous cultivars with showy colorful flowers have been bred since the early 1900s through selection of natural mutants and intraspecific crosses among a limited number of early ancestral taxa.