The endangered Lawson cypress occurs naturally only in the valleys of the Klamath Mountains on the borders of Oregon and California. It is a heavyweight among trees, as it can grow to 70 metres tall and 4 metres in diameter. The oldest living specimen is said to be over 1800 years old. The species is now threatened by a fungus, Phytophtora lateralis, which has apparently spread through human agency into the tree’s last outposts. It has no resistance to this fungus, which spreads through the roots, and the infected tree slowly dies.
The Lawson cypress was first brought to Europe in 1854, being named after the Scottish Lawson & Son nursery. It soon proved incredibly variable: from a single seed batch seedlings might be obtained showing great variations in habit and colour. In western Europe the Lawson cypress varieties are among the most popular of garden conifers.
Although as a rule the species has not done well in Finland, there are happy exceptions. At Mustila, it has been grown since the early years of the Arboretum in a range of forms and varieties, with varying success. Even the hardiest have suffered damage above the snow line in the severest winters.