Leylandii – A Botanical Freak

Leylandii an evergreen coniferous tree of very fast rapid growth

There are almost as many of them in the UK as people, around 55 million at the last count and that was in 2011. For many they are the least loved of our common or garden trees, utilitarian, consigned to fill awkward or unsightly spaces. Evergreen and offering vigorous growth of around a metre a year, Britain’s tallest, at Bedgebury Pinetum in Kent, stands some 40 metres tall and is still growing, their dense structure provides a garden with much valued privacy. Out of control, though, they are the source of neighbourly spats, anti-social behaviour orders and the occasional fatality.

In these environmentally conscious times, their advocates point to some research conducted in 2000 that showed that the “finer, more complex structure of their foliage” was 40% better at filtering out polluting particulates from the air than other native species such as hawthorn. Planted near busy roads they can provide increased protection against particulate pollution all the year round.

The principal objection to x Cupressocyparis leylandii, to give leylandii their current botanical name, is that they are neither native nor particularly accommodating to wildlife. Indeed, they are not found in the wild and their emergence as a garden staple is a relatively recent phenomenon, the result of a chance discovery in an estate in North Wales.

John Naylor, after receiving Leighton Hall, near Welshpool in Powys, as a wedding present in 1847 from his uncle, Christopher Leyland, commissioned Edward Kemp, who had trained under Paxton at Chatsworth, to landscape the grounds. New species of conifer discovered and imported from the west coast of North America to Britain by plant hunters such as David Douglas and William Lobb were all the rage amongst landowners in mid-19th century Britain and Naylor was no exception.

Around 1857 he planted a grove of coastal redwoods, some of which now stand some forty metres tall and make up the largest and oldest collection in Europe. This was extended into a pinetum over the next decades, and the collection, including specimen pines, firs, monkey puzzles, spruce, hemlock, and cedars, now makes up a Grade 1 listed arboretum, now managed by the Royal Forestry Commission.

Naylor’s son, Christopher, after a career in the Navy, settled down at Leighton Hall. In 1888, while working in the pinetum nursery on a batch of Nootka cypress seedlings, he noticed that six were displaying unusual characteristics. He isolated them, planted them on, and they grew. What he had come across was a cross-pollination of a female Nootka cypress with a nearby Monterey, producing a plant which combined the hardiness of the Nootka with the fast growth of the Monterey. Although both types of cypress are native to the United States, they are found a long way from each other in the wild and such an event would not have occurred other in the artificial environs of Leighton Hall.

Christopher inherited Haggerston Castle in Northumbria in 1891 and, after changing his surname to Leyland as a mark of respect to his benefactor, moved up north to modernise the property, taking his six hybrid plants with him. They were planted out in the grounds and not only did they survive the harsh salt-laden winds sweeping in from the North Sea but grew rapidly. Cuttings were taken at various intervals and planted on the estate, and three were planted in nearby Kyloe Woods in 1897 and another in 1906.