Chamaecyparis Spach (1841), in the family Cupressaceae, contains 8 species of trees from Eastern Asia and North America, of which Lawson’s cypress, C. lawsoniana (Murray) Parl., is the most common.

Description Trees to around 40m in height, or shrubs, usually pyramidal when young. The leaves are small, scale-like, overlapping, in flat fans. Juvenile leaves are small needles. The male flowers are small, often reddish before the pollen is shed; the females are usually bluish. Pollination is by wind. The cones are small, 5mm to 2cm across, of 4–6 tightly packed, horned scales, ripening in 1 year, or in 2 years in the case of the Nootka cypress, C. nootkatensis (D. Don) Spach. Seeds 2 per scale.

Key Recognition Features Flat fans of aromatic foliage and small, almost spherical cones.

Evolution and Relationships Close to Cupressus, which has larger cones that ripen over two or more years. The hybrid x Cupressocyparis leylandii shows how close the 2 genera are.

Ecology and Geography In forests, usually in moist climates with a wet summer. Lawson’s cypress and Nootka cypress are found on the Pacific coast from Alaska to north California, and the white cypress, C. thyoides (L.) Britt., Sterns & Pogg., is wild from Maine to Mississippi. Chamaecyparis pisifera (Sieb. & Zucc.) Endl. and C. obtusa (Sieb. & Zucc.) Endl. are wild in Japan, and C. formosensis Matsumura is found in Taiwan.

Comment Lawson’s cypress and both Japanese species are exceptionally variable and have produced many variegated, blue, and gold forms and other strange sports, which are commonly cultivated. The Pacific coast species are valuable for their timber.