Hydrangea petiolaris, a climbing hydrangea (syn: Hydrangea anomala subsp. petiolaris), is a species of Hydrangea native to the woodlands of Japan, the Korean peninsula, and on Sakhalin island of easternmost Siberia in the Russian Far East.Hydrangea petiolaris is sometimes treated as a subspecies of the closely related Hydrangea anomala from China, Myanmar, and the Himalaya, as Hydrangea anomala subsp. petiolaris.