It’s the season for peonies, those sweet-smelling flowers with their abundant layers of petals. Most peonies are solid-colored, but one type, Paeonia suffruticosa subspecies rockii, has dark purple splotches at the centermost tips of its petals, adding a violet ring to the otherwise white blossoms. Austrian-American botanist Joseph Rock collected seeds from this particular peony during an expedition to northwestern China on behalf of Harvard University’s Arnold Arboretum. Accordingly, the peony (which is a tree peony, as opposed to the herbaceous peonies often sold as cut flowers) is called Rock’s peony.
Rock collected seeds from that plant, and many others, during a 1924-1927 expedition to China’s Gansu province. At that time, Gansu included most of what are now the northwestern regions of Ningxia and Qinghai, as well as some of the northeastern Tibetan province of Amdo. It was at the Choni Monastery in Amdo that Rock scouted and collected seeds from the tree peony that would bear his name.
Rock got to Choni just in time. “The original plant was destroyed in 1928 when Muslim soldiers attacked and burned Choni to the ground,” writes forestry scholar Jeffrey Wagner in his article, “The Botanical Legacy of Joseph Rock,” adding that no other example of the subspecies had been found since in China.