Atlantic White Cedar Chamaecyparis thyoides (L.) B.S.P.

Chamaecyparis thyoides Gregory J. Edinger

Chamaecyparis thyoides
Gregory J. Edinger

Class
Pinopsida (Conifers)
Family
Cupressaceae (Cypress Family)
State Protection
Threatened
Listed as Threatened by New York State: likely to become Endangered in the foreseeable future. For animals, taking, importation, transportation, or possession is prohibited, except under license or permit. For plants, removal or damage without the consent of the landowner is prohibited.
Federal Protection
Not Listed
State Conservation Status Rank
S2
Imperiled in New York - Very vulnerable to disappearing from New York due to rarity or other factors; typically 6 to 20 populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines.
Global Conservation Status Rank
G4
Apparently Secure globally - Uncommon in the world but not rare; usually widespread, but may be rare in some parts of its range; possibly some cause for long-term concern due to declines or other factors.

Contents

  1. Summary
  2. Conservation and Management
  3. Habitat
  4. Range
  5. Identification Comments
  6. Taxonomy
  7. Additional Resources
  8. About This Guide

Summary

Did you know?

Atlantic white cedar trees grow slowly and may live for more than 1000 years. The wood is very resistant to decay. Trees buried in peat bogs for decades have been recovered still in excellent condition. One of the largest inland Atlantic white cedar wetland complexes in the world was located along the Wallkill River flood plain in southern Orange County. Originally over 50,000 acres the "Drowned Lands" swamp was almost completely converted to agriculture by the 1970s.

State Ranking Justification

There are 16 existing populations and about half of them are large and protected. The remaining populations are small with usually under 100 trees but some of them are in protected areas. While some small occurrences may still be discovered it is not expected that additional large populations would be found. All of the historical populations have been checked.

Short-term Trends

Short-term trends are stable with no big changes in existing populations.

Long-term Trends

In the last 100 years there has been a decline in Atlantic white cedar swamps in western Long Island and the lower Hudson area including the destruction of some very large swamps in Nassau and Orange counties. Many of the remaining swamps are within developed landscapes without large natural buffers.

Conservation and Management

Threats

Some unprotected white cedar swamps are subject to habitat loss by logging and development. Beaver activity may cause high water levels to kill trees.

Conservation Strategies and Management Practices

Trees need to be protected within their wetlands by providing large enough natural buffers to preserve hydrologic régimes and to prevent direct destruction of the swamps and trees.

Habitat

Habitat

Chamaecyparis thyoides is found in swamps and ponds, typically at sites with a high water table and deep organic soils. Unlike Northern-White Cedar (Thuja occidentalis), it is not associated with high pH sites or the influence of calcareous bedrock or groundwater. Historically Atlantic White-Cedar swamps covered large areas in the coastal plain and along floodplains.

Associated Ecological Communities

  • Coastal plain Atlantic white cedar swamp (guide)
    A swamp that occurs on organic soils along streams and in poorly drained depressions of the coastal plain. Atlantic white cedar makes up over 50% of the canopy cover. In mixed stands in New York, red maple is the codominant tree.
  • Coastal plain pond (guide)
    The aquatic community of the permanently flooded portion of a coastal plain pond with seasonally, and annually fluctuating water levels. These are shallow, groundwater-fed ponds that occur in kettle-holes or shallow depressions in the outwash plains south of the terminal moraines of Long Island, and New England. A series of coastal plain ponds are often hydrologically connected, either by groundwater, or sometimes by surface flow in a small coastal plain stream.
  • Inland Atlantic white cedar swamp (guide)
    A swamp that occurs on organic soils (usually peat) in poorly drained depressions and along pond edges in southeastern New York and northern New Jersey. The characteristic tree is Atlantic white cedar. In mixed stands the codominants are typically red maple, black gum, and eastern hemlock.
  • Pitch pine-blueberry peat swamp* (guide)
    A swamp that occurs in shallow depressions in sand plains where peat has accumulated over a poorly drained sandy soil. This soil has a horizon cemented by iron oxide; the cemented horizon impedes drainage and causes seasonal flooding. The dominant tree is pitch pine. Gray birch and red maple are present at a low density. The canopy is open, with about 50 to 60 percent cover. * probable association but not confirmed.
  • Red maple-blackgum swamp* (guide)
    A maritime, coastal, or inland hardwood swamp that occurs in poorly drained depressions, sometimes in a narrow band between a stream and upland. Red maple and blackgum are often codominant or blackgum may be the dominant tree. Pitch pine may occur on drier hummock islands in pine barrens settings. * probable association but not confirmed.

Associated Species

  • Acer rubrum
  • Bidens frondosa (devil's beggar-ticks)
  • Chamaedaphne calyculata (leatherleaf)
  • Clethra alnifolia (coastal sweet-pepperbush)
  • Myrica gale (sweet gale)
  • Myrica pensylvanica
  • Nyssa sylvatica (black-gum, sour-gum)
  • Rhododendron viscosum (swamp azalea)
  • Sphagnum
  • Vaccinium corymbosum (highbush blueberry)

Range

New York State Distribution

In New York this species is known only from the Long Island and lower Hudson Valley regions.

Global Distribution

This tree is known from all the Atlantic Coast states, and west along the Gulf Coast as far as Mississippi.

Identification Comments

General Description

Atlantic White Cedar is an attractive, small to medium-sized evergreen tree, its crown generally forming a narrow spire or column shape. The dark, shiny green foliage is arranged into 2-ranked branchlets, and the tiny (2-4mm) scale-like leaves are imbricate (overlapping like shingles), ovate and usually glandular. The brownish-gray bark is divided into long, thin, tight strips. Thecones are glaucous purple or blue capsules, covered by 4 to 6 non-overlapping scales

Best Life Stage for Proper Identification

This species may be identified from either the cones or sterile branches.

Similar Species

Thuja occidentalis has flattened branchlets, its cones have overlapping scales, and it is typically found further inland and north then Chamaecyparis thyoides. Juniperus virginiana has sharp, needle-like leaves, its fruits are fleshy "berries" rather than capsules, and it is usually found in drier habitats.

Best Time to See

May be identified all year round.

  • Vegetative
  • Fruiting

The time of year you would expect to find Atlantic White Cedar vegetative and fruiting in New York.

Atlantic White Cedar Images

Taxonomy

Atlantic White Cedar
Chamaecyparis thyoides (L.) B.S.P.

  • Kingdom Plantae
    • Phylum Coniferophyta
      • Class Pinopsida (Conifers)
        • Order Pinales
          • Family Cupressaceae (Cypress Family)

Additional Common Names

  • Southern White Cedar
  • Swamp-cedar
  • Coast-cedar

Additional Resources

Best Identification Reference

Flora of North America Editorial Committee. 1993. Flora of North America, North of Mexico. Volume 2. Pteridophytes and Gymnosperms. Oxford University Press, New York. 475 pp.

Other References

Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Haines, Arthur and Thomas F. Vining. 1998. Flora of Maine. A Manual for Identification of Native and Naturalized Vascular Plants of Maine.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.

Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.

Rhoads, Ann F. and Timothy A. Block. 2000. The Plants of Pennsylvania, an Illustrated Manual. University of Pennsylvania Press, Philadelphia, PA.

Rhoads, Ann F. and Timothy A. Block. 2005. Trees of Pennsylvania. A Complete Reference Guide. University of Pennsylvania Press, Philadelphia, PA.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York

Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).

Links

About This Guide

Information for this guide was last updated on: February 29, 2012

Please cite this page as:
New York Natural Heritage Program. 2023. Online Conservation Guide for Chamaecyparis thyoides. Available from: https://guides.nynhp.org/atlantic-white-cedar/. Accessed May 29, 2023.

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