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The Atlantic white-cedar, or swamp cedar, (Chamaecyparis thyoides) is an evergreen tree native to Atlantic coastal areas from southern Maine to northern Florida and along the Gulf coast from the Florida panhandle west to Mississippi. Although it is often commonly referred to a cedar, C. thyoides is actually a cypress, in family Cupressaceae. It is also commonly known as Atlantic white cypress, or white cedar false cypress.
Atlantic white cedar trees most frequently grow in lowland fresh water swamps and bogs within 210 km (130 miles) of the coastline, usually where they are regularly inundated with water. They occasionally, but rarely, occur above 50 m (150 feet) in altitude. Trees form dense stands in acidic peat (also called muck). Especially in the south, sandy soils also support these trees. Atlantic white cedars have a very patchy distribution across their range, reflecting these specific habitats. They can be found in greatest abundance in the Great Dismal Swamp of North Carolina, the Florida Panhandle, and southern Alabama. In other parts of their range they are scattered in smaller, isolated stands.
As seedlings, Altantic white-cedars can grow quickly, up to 0.5 meters (1.5 feet) per year. Adult tree size averages 28 meters (90 feet) tall. Trees have deeply ridged, grey to red-brown colored bark that peels off in long strips from the trunk. Their branches support fanlike sprays of scaly, blue-green leaves that give off an aromatic, cedar-like scent. The shallow roots of Atlantic white-cedars usually do not grow below the top 1-2 feet (0.3-0.6 m) of peat. This makes the trees susceptible to almost any wind. Although these trees are long-lived and can reach 1,000 years of age, the stands they live in rarely survive more than 200 years.
Atlantic white-cedars are monoecious, meaning that they produce separate male and female flowers. The small green female flowers develop on short shoots and tiny yellow or red male (pollen-producing) flowers appear on the tips of branches. They start shedding pollen in April. Blue-green fertilized cones mature into brown spheres about 6 mm (0.2 in) across. Between October and March the cones open to release 5-15 winged seeds, dispersed mostly by wind. Mature trees (usually 15 years of age or older) produce a large number of seeds each year.
Atlantic white-cedars often grow in a pure stands surrounded by other tree species. These can include black gum, gray birch, yellow birch, red maple, sweet bay magnolia, white bay magnolia and water gum, and/or associated conifers such as eastern white pine, pond pine, eastern hemlock, tamarak, and black spruce. Many brush species grow in thick impenetrable tangles in the stand understory. Atlantic white-cedar stands provide cover and food for a large number of birds and other animals. Yellow-throated warblers, prairie warblers, and hooded warblers nest close to the ground in Atlantic white-cedar stands, and pileated woodpeckers nest in tree cavities. White tailed deer and mice browse on Atlantic white cedar foliage and bark, black bears mark the trees to define their territories.
The Atlantic and Gulf populations C. thyoides are disjunct, and some sources recognize them as separate subspecies: C. thyoides thyoides and C. thyoides henryae, respectively. Others consider them as two separate species or variants. For a time the IUCN considered the gulf variety (C. thyoides henryae) “Near Threatened," as stands have been heavily harvested for commercial uses ever since the revolutionary war. Though large, old individuals are lacking, overall tree numbers appear to be recovering, so the subspecies has been relisted as “of least concern.”
The light, fragrant, resistant wood of Atlantic white-cedar has been exploited for many commercial uses including fuel, ship-building, shingles, milled lumber, charcoal, household items, barrels, duck decoys and, during the civil war, charcoal for gunpowder. Atlantic white-cedar wood is still used for telephone poles, posts, siding, furniture, and paneling. The species has been cultivated for horticulture for ornamental planting, and in some parts of the south it is grown for Christmas trees.
(Chesapeake Bay Program, 2012; Earle 2014; Farjon 2013 a,b; Laderman 1989; Little and Garrett 1990; Seiler et al. 2015; Tirmenstein 1991; Wikipedia 2015)