The Introduction of Paperbark Maple to the United States

Paperbark maples (Acer griseum) are known for their distinctive appearance. Paper-thin, peeling bark curls away from muscular, red-orange trunks. It produces small yellow flowers in spring. The leaves are green in summer and crimson in fall.

There are over 20 paperbark maples across the 281-acre landscape of the Arnold Arboretum of Harvard University. This map shows the year each maple was accessioned, or added to the Arboretum's living collection.

The story of these trees reflects the Arboretum’s ethos of exploration and partnership that arose in the twentieth century and continues to this day, as well as its long-term commitment to the stewardship and conservation of threatened species.

No paperbark maples grew in North America 150 years ago. The majority of the world’s roughly 130 maple species are native to eastern Asia.

In the nineteenth century, areas of eastern Asia were opened to traders and travelers from Western countries. These included enthusiastic plant collectors seeking novel species to understand species diversity and support a burgeoning horticultural industry. The Arnold Arboretum was founded during this time.

The Arboretum was founded in 1872 with a mission to expand public understanding of woody plants and their place in the world. Arboretum founding director Charles Sprague Sargent wanted to create a learning landscape that could be enjoyed by scientists and visitors. For the next half century, Sargent, along with a team of dedicated colleagues, worked to cultivate a diverse landscape of plants.

The Arboretum’s founding documents set a goal of amassing a wide selection of trees. Sargent worked with professional and amateur botanists to gather seed from gardens and wild spaces alike. Many of these plants came from the east coast of the United States.

At the turn of the twentieth century, the Arboretum started getting plant material from much further afield by sponsoring collecting trips abroad and sending plant collectors across the globe to collect seed and herbarium vouchers. Newly accessible regions of eastern Asia had similar flora to areas in North America, and botanists were eager to collect specimens.

The Arboretum sponsored a two-year trip led by Ernest Wilson, a young plant collector who had previously collected in China on behalf of Britain’s Veitch Nurseries.

From 1907-1909, Wilson travelled around China, collecting plant material and taking photographs. His travel documents imply the rigors of his trip. This one granted him permission to carry hunting guns and ammunition.

After his travels through China in the early twentieth century, Wilson introduced the paperbark maple in North America. He sent two seedlings he’d collected in Hubei Province in central China to the Arboretum. These specimens are now over 100 years old.

The trees produced seed. Over the next several decades, the Arboretum distributed seed packets, seedlings, and scions to botanic institutions across North America, playing a crucial role in the distribution of the tree.

Today, the paperbark maple has secured a celebrity and popularity among scientists and gardening enthusiasts alike.

In its native habitat, the tree is categorized as endangered by the International Union for Conservation of Nature due to threats such as habitat destruction.

Analysis revealed that most of the paperbark maples in the United States and United Kingdom descended from a single introduction—one collected by Wilson in 1901. This is problematic, as species with less genetic diversity are less resistant to pests and disease.

In 2015, the North America-China Plant Exploration Consortium (NACPEC), a collaboration between North American and Chinese botanical institutions, embarked on a plant collecting trip aimed at sampling the majority of the known populations of paperbark maple.

The collectors traced a route of over 2,200 miles in central China, sampling 66 trees to gather DNA information, seed, and herbarium vouchers. The data are helping researchers learn more about the genetic variation of extant populations of paperbark maple.

The story of paperbark maple is still unfolding. At the Arnold Arboretum, we remain committed to the cultivation and conservation of this striking tree.