Tony Kirkham finds planting opportunities within a centuries-old landscape.
As head of the arboretum at the Royal Botanic Gardens, Kew, I would walk the collection each day, choosing a different route and corner of the three-hundred-acre landscape. On the walks, I observed the growth of newly planted trees and built up a knowledge of the collection. I wanted to understand where gaps occurred and what we should plant to improve the wealth and diversity of the woody collections. I kept an eye out for important but ailing plants that should be repropagated. This daily practice remained valuable no matter how long I worked at Kew—a tenure that spanned forty-three years in various roles.
I describe the arboretum at Kew as a living reference library of woody plants from every corner of the temperate world that will grow outdoors (near London) without any form of protection during the winter. However, overseeing a collection like this isn’t just about planting trees as they become available and looking after them. The collection is visited by two million people per year. It must meet the demands of a school educational program and remain one of the most diverse and authentic scientific collections of temperate trees in the world.
The age of Kew only adds to the challenge: how does a curator not only maintain but hopefully improve upon a tree collection that has been tended for more than 250 years? The gardens at Kew date to 1731, when King George II’s son, Frederick Prince of Wales, leased the estate and began to develop the grounds. After his death, his wife, Princess Augusta, continued his work, and in 1759, on the advice of Lord Bute, her horticultural advisor, she created a nine-acre botanic garden with the planting of several newly introduced trees that we now know as the “Old Lions.” Some of these are still growing today, including a maidenhair tree (Ginkgo biloba) and a black locust (Robinia pseudoacacia). By 1768, the collection included almost five hundred hardy trees and shrubs, but it wasn’t until 1840 that Kew Gardens was placed under direct government control and the first director, William Hooker, was appointed to restore and expand the arboretum.
It has been an amazing privilege to oversee such a collection, following in the footsteps of remarkable people like William Jackson Bean, the assistant curator of the arboretum between 1900 and 1922. He authored the monumental reference work Trees and Shrubs Hardy in the British Isles, which is now online (with regular revisions) as Trees and Shrubs Online, courtesy of the International Dendrology Society. Even within such a storied landscape, the collections are ever-changing. Managing those changes is the essential work of a curator.
A landmark turning point for the arboretum occurred on the night of October 16, 1987, when a hurricane struck the southeast of England, wreaking havoc to trees and woodlands, felling over fifteen million trees in its wake. At Kew, over seven hundred mature trees were lost that night. I remember waking up to loud bangs and crashes and my steel dustbin rolling down the road. I got up to retrieve it and was concerned by the strength of the winds. The following morning, all came to light with the news showing images and footage of devastation across the south of England.
I was a young supervisor in the arboretum at the time, and when I finally made the journey into work, I immediately went out into the landscape to see how all my arboreal friends had fared through the night. As I picked my way through the limbs and uprooted trees, all I could think was “doom and gloom.” It took us over three years to finally clear away the fallen, damaged trees. As I look back now, I consider this hurricane to be one of the best things that happened in the twentieth century for trees in the United Kingdom. It raised public awareness of the importance of trees nationally. At Kew, a new plant exploration program was started to replenish the gaps in the collections created by the storm, and new arboricultural practices were developed to improve the health of the remaining trees.
I was fortunate to be a part of the team sent to collect new documented seed material to rebuild the tree collections. The species on the target lists and the parts of the world that would be visited were determined by an audit of what was still represented in the collections after the storm, looking at the taxonomic and geographic weaknesses. The first expeditions were to western China, South Korea, Taiwan, the Russian Far East, and Japan, and the material brought back over the past thirty-four years has greatly enriched the diversity and provenance of the tree collections. Much of this has not been done alone. Working with colleagues at other arboreta around the world has been important for sharing ideas, collections, and stories.
I have never been one for pushing the boundaries of hardiness, especially as we increasingly experience unpredicted weather patterns. Still, I have been able to plant and establish species that we could not have grown outdoors forty years ago: for instance, the Taiwan coffin tree (Taiwania cryptomerioides), Kashmir cypress (Cupressus cashmeriana), and the paraná and bunya pines (Araucaria angustifolia and A. bidwillii), both from the Southern Hemisphere. On my daily walks through the arboretum, I would look for locations to position these and others. As curators, we all have our favorite areas and genera of trees, but we must ensure that other parts of the collection aren’t neglected. I found that the wire cages used to protect our young trees provided a helpful visual cue. The cages are retained for five years, so I would stand in the arboretum and turn 360 degrees. If I failed to see one of the cages, this would signal to me a target area for succession planting.
Several new introductions into the arboretum come to mind as highlights. In the autumn of 1996, on a collecting trip to China, I was fortunate to be granted permission to visit Jinfushan, a mountainous preserve in the upper reaches of the Yangtze River, to see the Chinese silver fir (Cathaya argyrophylla). This species, discovered in 1955 by Chinese scientists, was something we had only heard about but never seen. We found it growing on the limestone bluff but could not collect seed, owing to a national embargo. Two years later, the embargo was lifted, and seed was distributed to forestry institutes and botanic gardens. The Forestry Commission’s Bedgebury Pinetum was the first to grow this tree in the United Kingdom, and its curator gave me a two-year-old plant for our collection. This can be a miffy species and finding the best planting position can be difficult. More by luck than judgement, I got it right. The plant at Kew is now a beautiful specimen about twenty feet high. It has produced viable seeds, and the first generation of ex situ propagated seedlings has now been planted out in the arboretum, helping conserve this rare tree.
Another successful introduction is the Chinese hickory (Carya cathayensis). In 2008, on a trip to China to follow in the footsteps of Ernest Henry Wilson, I visited a market in Shanghai and saw nuts of the rare species being cooked and sold as candied pecans. We bought a kilo of uncooked seeds, and the propagator in Kew’s nursery, after much experimental work, successfully germinated the seed and grew over twenty plants that are now sited in various locations across the arboretum. These are now gorgeous trees. They are very well-behaved, needing little if any formative training and producing a straight tapered trunk with an even distribution of lateral branches. The species is perfectly hardy in the United Kingdom.
For me, one of the main criteria for a successful and healthy treescape and collection is continual succession planting, maintaining a healthy population with generations of individual species, like a family, ranging from the great grandparents (the Old Lions) to the great-grandchildren (the newly planted trees this year). It was so rewarding to walk the collections seeing new introductions like the delicate Taiwan beech (Fagus hayatae), which we introduced as seed to the West in 1992, growing into strong, attractive specimens and enhancing the conservation value of the arboretum. Some of these, we hope, will be the Old Lions of tomorrow.
Tony Kirkham retired as head of the arboretum at Royal Botanic Gardens, Kew, in the summer of 2021. Among other honors, he was appointed to the Most Excellent Order of the British Empire in 2019.
From “free” to “friend”…
Established in 1911 as the Bulletin of Popular Information, Arnoldia has long been a definitive forum for conversations about temperate woody plants and their landscapes. In 2022, we rolled out a new vision for the magazine as a vigorous forum for tales of plant exploration, behind-the-scenes glimpses of botanical research, and deep dives into the history of gardens, landscapes, and science. The new Arnoldia includes poetry, visual art, and literary essays, following the human imagination wherever it entangles with trees.
It takes resources to gather and nurture these new voices, and we depend on the support of our member-subscribers to make it possible. But membership means more: by becoming a member of the Arnold Arboretum, you help to keep our collection vibrant and our research and educational mission active. Through the pages of Arnoldia, you can take part in the life of this free-to-all landscape whether you live next door or an ocean away.