Although its popularity may be declining since its heyday in the last century, Leyland cypress is still widely planted by gardeners looking for quick hedges and privacy screens. Often they end up with more than they bargained for, right down to legal disputes with neighbours and their city. While much safer for drains and foundations than many other more widely loved trees, and a top-rate screen from a highway, it has a reputation for easily growing out of bounds. Smart gardeners with small gardens should probably avoid it, unless they love trimming hedges.
As controversial as it is, the history of this tree is an insight into the past, and just one of the many fascinating stories about where our plants came from. We plant so many different trees, but we rarely think about their origins – maybe we think they just grow on trees. You will not find the majority of the plants we grow in our gardens out in the natural world. They are often the product of complex and skilled breeding programs stretching over decades, but they are just as often the result of pure serendipity, which is how we came to have the Leyland cypress.
In the affluent and relatively calm period that went from the middle of the 19th century to World War I, gardening was a popular pursuit of the wealthy classes on both sides of the Atlantic, but especially in the UK. It was a time when the owners of grand estates vied with each other to show off the latest arrivals from around the world, and laced their teatime conversations with Latin names and botanical speculations. John Naylor was certainly a member of that privilege class, living at Leighton Hall, just across the English border in Wales. The estate dated back to 1541, and in 1845 Christopher Leyland, a wealthy banker, had bought it. Two years later, he gave it as a wedding present to his favorite nephew, John.
The first task was to rebuild the house, which he did at a cost of £275,000 (perhaps $40 million today). For the grounds he hired the landscape designer Edward Kemp. Still a young man, Kemp was at the start of an illustrious career that would put him on a par with the more famous Joseph Paxton as a designer in the English Landscape Style. Trees were a critical element in that style, and Kemp made sure to include a wide variety of them, from around the world. The extensive grounds became an arboretum of the rare and exotic.
The One in a Million Cone
Among those trees was Nootka cypress, Cupressus nootkatensis, a tree widespread along the Pacific Northwest coast of North America. This forest tree grows from the Siskyou Mountains in northern California all the way to Prince William Sound in Alaska. In 1888, while walking around his estate, John Naylor picked a cone from one of these trees and had his gardeners grow some of the seeds for him. Perhaps he simply wanted to have a few more of these handsome trees on his grounds.
When John died, one of his three sons, Christopher John, inherited Leighton Hall. A few years later, in 1891, Christopher also inherited the estates of an uncle, Thomas Leyland. The major part was Haggerston Castle, on 23,000 acres near the border with Scotland. As was typical of complex inheritances, this caused Leighton Hall to pass to a younger brother of John Naylor, and Christopher took his uncle’s name, becoming Christopher Leyland.
An ambitious gardener with a keen interest in trees, Christopher developed Haggerston Castle into a grand rival for his father’s property, and during the move took with him six of those cypress seedlings to plant on his new grounds.
In 1911, back at Leighton Hall, another nephew was to repeat the random act of John Naylor by also picking up a cone, but this time from a Monterey cypress growing just 150 feet from that original Nootka cypress. Monterey cypress, Cupressus microcarpa, today grows wild only in two small areas on the coast of California, both of them nature reserves.
Christopher Leyland noticed that two of his seedlings were remarkably vigorous and he called one ‘Haggerston Grey’ and the other ‘Green Spire’. The best two trees from that second cone were called ‘Leighton Green’ and ‘Naylor’s Blue’.
The Botanists Get to Work
At this point, the botanists join the story. In 1925 a Cambridge professor, William Dawson, was a house guest at Haggeston Castle. Leyland had already noticed the virtues of his seedlings, chiefly in their rapid growth and resistance to salt-spray from the ocean nearby. He asked Dawson to take some samples to William Dallimore, the conifer expert of the time. Dallimore had worked his way up from a humble student gardener at the Royal Botanic Gardens, Kew, to become an authority, and his recent book, Handbook of Coniferae and Ginkgoaceae, was considered the definitive work. He pored over the specimens and pronounced them to be hybrids between the Nootka and Monterey Cypresses. Dallimore and his associate Jackson published their findings in the Kew Bulletin of March, 1926, and named the tree Cupressus x leylandii, in honor of Christopher Leyland. Cuttings were rooted and planted at several botanic gardens. One of the original trees was now 35 feet tall, and by 1930, it is listed in the catalogue of the famous Hilliers Nursery. Almost all plants in gardens derive from the ‘Haggerston Grey’ plant, which despite its name is of course green.
Five of the original six trees still survive exactly where they were first planted, but Haggerston Castle does not. Mr. Leyland died the same year he achieved immortality in the name of his tree, and the castle was demolished. Leighton Hall still survives, although today it is unoccupied.
Soon popular in Britain for hedging, the first plants crossed the Atlantic in 1941, when rooted cuttings arrived at the Institute of Forest Genetics at Placerville, California. From there trees went to the Strybing Arboretum in San Francisco and to the University of Washington Arboretum in Seattle. In 1953, Leyland cypress arrived in the east at the U.S. National Arboretum. In the 1960s, Clemson University in South Carolina distributed plants widely to southern nurseries, and the tree became even more popular than it was in Europe. The spread of suburbia, and the new mass-need for instant privacy between homes was a marketing opportunity nurseries across America and Europe were quick to grasp, and millions upon millions of plants were sold during the heyday of Leyland cypress.
In recent decades the tree has fallen out of favor, and has been widely replaced with the slightly less aggressive Thuja ‘Green Giant’, another chance hybrid, this time between Japanese Thuja (Thuja standishi) and Western Redcedar (Thuja plicata). Curiously, recent research into the genetics of cypress suggests that Monterey cypress is closely related to a rare Asian species and much more genetically distinct from Nootka cypress than was originally realized. A number of experts have moved it, and its Vietnamese relative, to the genus Xanthocyparis.
Based on this new information, Leyland’s tree is probably more correctly called x Cupressocyparis leylandii. Mr. Leyland’s miracle cypress turns out to be more like ‘Green Giant’ than thought, and these two trans-Pacific meetings of gene pools both bestow remarkable hybrid vigor on their famous offspring.