2015 North America-China Plant Exploration Consortium (NACPEC) Expedition to collect Acer griseum
Ernest Henry Wilson’s favorite maple was Acer griseum, a species he successfully collected on two separate occasions in China – once in 1901 on his first expedition for Veitch Nursery of England, and again in 1907 on his first expedition for the Arnold Arboretum. Although paperbark maple is a well-known and popular tree in our gardens and arboreta, amazingly it is but from these two introductions that the entire pool of germplasm in the west is derived. (Note: the 1994 NACPEC expedition yielded ten seedlings, but those plants have only recently started to produce seed and have not made their way into other gardens, or the commercial trade). A rare tree even in Wilson’s time, Acer griseum is now threatened with extinction, the few wild populations scattered from Gansu Province in the west to Shanxi Province in the east. Because so little is known about the genetic variation within and among these different populations, the purpose of this NACPEC expedition was to survey as many of the known populations as possible, sampling leaf tissues for DNA extraction and genetic characterization, and when possible, collecting seeds for ex situ conservation.
The trip lasted from the 1st to 18th of September of 2015. Participants included Curator of Living Collections Michael Dosmann, Tony Aiello of the Morris Arboretum of the University of Pennsylvania, Kris Bachtell of the Morton Arboretum, and Wang Kang of the Beijing Botanical Garden. Unlike other expeditions that may have stuck to just one geographic area, these explorers spent much of their time in transit in order to visit as many populations as possible during the two-week trip. Their 2,237-mile (3600-kilometer) journey took them to nine different populations scattered across six provinces and one municipality. Typically the group spent an entire day and often part of the night driving to a new location, followed by a day or two of hiking and discovery. While some of the populations comprised scores of individuals including newly regenerating seedlings, sadly a number of populations were in decline and had just a few trees. On several occasions, trees had been cut back or coppiced to the ground by local farmers gathering wood for fuel. Among nine wild populations, only a single tree bearing a few seeds was found. A second tree, growing at the Xi’an Botanic Garden, also bore seed. The team collected germplasm from both and it will be exciting to see how the new plants grow in the Arboretum’s collection. It will also be exciting to see the results of their conservation project looking at the DNA from all the populations.
In addition to herbarium, DNA, and seed collections of Acer griseum (66 trees sampled), the travelers made seven collections of other plants spotted in close proximity to the maples. Among these was an impressive specimen of the paperbark filbert, Corylus fargesii, which stood some 80 feet (24 meters) tall.