The Leyland Cypress is often referred to as just Leylandii. It is a fast-growing evergreen tree much used in horticulture, primarily for hedges and screens. It's name originates from C.J. Leyland, a sea captain, who grew some of the first hybrids on his property, Haggerston Castle, in Northumbria, in 1888.
The Leyland Cypress is a hybrid between the Monterey Cypress, Cupressus macrocarpa, and the Nootka Cypress, Cupressus nootkatensis, family Cupressaceae, both are natives of the mountains of the North American west coast. The hybrid has arisen on nearly 20 separate occasions, always by open pollination, showing the two species are readily compatible and closely related.
Leyland Cypresses are commonly planted in gardens to provide a quick boundary or shelter hedge. However, their rapid growth (up to a meter per year), heavy shade and great potential height (often over 20 m tall in garden conditions, they can reach at least 35 m) make them problematic.
In Northern areas where heavy snows occur, this plant is also susceptible to broken branches and even uprooting in wet, heavy snow.
Note: Caution should be exercised when handling tree clippings - after trimming, for example. The sap can cause skin irritation in susceptible individuals.