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Lawson's Cypress (Chamaecyparis lawsoniana), is an evergreen coniferous tree in the genus Chamaecyparis, in the cypress family Cupressaceae. It is also known as Port Orford Cypress, or more confusingly as Port Orford Cedar; as it is not a cedar, many botanists prefer to avoid that name. It is native to the southwest of Oregon and the far northwest of California in the U.S.A.. It was first discovered near Port Orford in Oregon and introduced into cultivation in 1854, by collectors working for the Lawson & Son nursery in Edinburgh, Scotland.
It is a large tree, regularly reaching 60 m (200 ft) tall, with feathery foliage in flat sprays, usually somewhat glaucous blue-green in colour. The leaves are scale-like, 3-5 mm long, and produced on somewhat flattened shoots. The seed cones are globose, 7-14 mm diameter, with 6-10 scales, green at first, maturing brown in September, 6-8 months after pollination. The male cones are 3-4 mm long, dark red, turning brown after pollen release in February-March.
In the wild, the species is seriously threatened by a root disease caused by the introduced fungal pathogen, Phytophthora lateralis. This disease is also a problem for horticultural plantings in some parts of North America. The tree is sometimes killed, though less often, by other species of Phytophthora.
It is of great importance in horticulture, with several hundred named cultivars of varying crown shape, growth rates and foliage colour having been selected for garden planting.
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