An aromatic conifer named after the Scottish nursery Peter Lawson & Co., then run by Charles Lawson (1795-1873), where the first plants were raised from seed sent to Britain in 1854 by the nursery’s collector William Murray. Its name is sometimes written without the apostrophe. In North America it is called Port Orford Cedar, though it is no true cedar.

Native to a small coastal strip of the western USA, from south-west Oregon to north-west California. It grows in pure or mixed stands from sea level to 1,700m in the Siskiyou Mountains, where summers are relatively moist and cool. The pure form and cultivars are widespread in north-west Europe, especially Britain and Ireland.

Monoecious. Female cones mature in one season, releasing small winged seeds, dispersed by wind and water (as they float).

Tall (50m), usually with a drooping leader. Bark brown-red, spongy and thick (to 25mm) on mature trees, with vertical rounded ridges. Foliage fern-like in sprays, the leaves pointed but not sharp, smelling of parsley when crushed. Male cones crimson; female cones globular, small (1cm), green then brown, with 8-10 scales fused at the tip. Western Red Cedar and Leyland Cypress differ in scent, leader and cones.

Best in moist but not waterlogged soils. Cold-hardy but prone to forking from spring frosts and heavy snow. Foliage is very palatable to deer. An effective coloniser, it grows even in deep shade beneath mature conifers. Slow growth and slow self-pruning limit its commercial timber use. The pure form and cultivars make attractive landscape and windbreak trees, and can be clipped.

Given its shade tolerance, Lawson’s Cypress can be planted to help diversify monoculture plantations, especially those of Sitka Spruce (p. xxx), and provide diversity and year-round shelter to wildlife in stands of European Beech (p. xxx).

Considered threatened, with most old-growth forest felled. Surviving trees have succumbed to the introduced root disease Phytophthora lateralis. Access to remaining wild stands is restricted to aid conservation, while breeders are achieving some resistance. P. lateralis is present in Britain, Ireland, France and the Netherlands, though honey fungus is currently a commoner threat.

Its soft, orange-brown timber is durable and aromatic, traditionally used for many products, including, unusually, the shafts of superior wooden arrows. Beyond the pure form, many hundreds of cultivars are grown ornamentally, varying in size (semi-dwarf forms are very popular), form (columnar or weeping) and foliage colour.