Chamaecyparis thyoides (Atlantic White Cypress or Atlantic Whitecedar), is a species of Chamaecyparis, native to the Atlantic coast of North America from Maine south to Georgia, with a disjunct population on the Mexican Gulf coast from Florida to Mississippi. It grows on wet sites on the coastal plain at altitudes from sea level up to 50 m, more rarely in the foothills of the Appalachian Mountains up to 460 m altitude. The name is also sometimes wrongly cited as "Atlantic White Cedar", a name rejected by the American Joint Committee on Horticultural Nomenclature as it is a cypress, not a cedar.
It is an evergreen coniferous tree growing to 20-28 m (rarely to 35 m) tall, with feathery foliage in moderately flattened sprays, green to glaucous blue-green in color. The leaves are scale-like, 2-4 mm long, and produced in opposite decussate pairs on somewhat flattened shoots; seedlings up to a year old have needle-like leaves. The seed cones are globose, 4-9 mm diameter, with 6-10 scales, green or purple, maturing brown in 5–7 months after pollination. The pollen cones are purple or brown, 1.5–3 mm long and 1–2 mm broad, releasing their yellow pollen in spring.