Silas Little and Peter W. Garrett
Atlantic white-cedar (Chamaecyparis thyoides), also called southern white-cedar, white-cedar, and swamp-cedar, is found most frequently in small dense stands in fresh water swamps and bogs. Heavy cutting for many commercial uses during this century has considerably reduced even the largest stands so that the total volume of this species growing stock is not currently known. It is still considered a commercially important single species in the major supply areas of North and South Carolina, Virginia, and Florida.
Chamaecyparis thyoides (L.) Britton, Sterns & Poggenb.
Depressions in pine savannas, ditches, borrow pits.
Rare. Mar–Apr ; Oct–Nov . Thornhill 757 (NCSC). Specimens seen in the vicinity: Sandy Run [Hancock]: Sieren 3676 (WNC!), Taggart SARU 69 (WNC!); Sandy Run [ O’Berry ]: Weakley 7219 (NCU!). [= RAB, FNA, Weakley]
General: Cypress family (Cupressaceae). Native evergreen trees growing to 20 (-28) meters tall; trunks to 0.8 (-1.5) meters in diameter. Bark: reddish-brown, irregularly furrowed and ridged, peeling in long, fibrous strips, often partially twisted around the trunk. Branchlets are terete or rhombic in cross-section, in fan-shaped sprays, covered with dark blue-green, overlapping scale leaves to 2 mm long; facial and lateral leaves similar, usually with circular leaf glands. Seed cones are globose, 4-9 mm broad, bluish-purple to reddish-brown at maturity, with a somewhat crumpled appearance; scales 5-7. Native. The common name reflects its occurrence on the Atlantic coastal plain and its light-colored wood.
Variation within the species: populations of Atlantic white-cedar in Florida, Alabama, and Mississippi have been segregated as Chamaecyparis henryae Li (= C. thyoides var. henryae (Li) Little), based on differences in bark, branchlets, leaves, and fruit, but the species also is variable in the Atlantic coastal segment of its range and the Gulf coast segregate has not generally been accepted.
Arborvitae (Thuja occidentalis) can be distinguished from Atlantic white-cedar by its flattened branchlets with clearly differentiated facial and lateral leaves and its ellipsoid seed cones.
Distribution: Atlantic white-cedar grows in a narrow coastal belt 80 to 210 km (50 to 130 miles) wide from southern Maine to northern Florida and west to southern Mississippi. The scarcity of suitable growing sites makes distribution of the species within the coastal belt very patchy. The species is now classified as rare in Georgia, Mississippi, Maine, Maryland, New York, New Hampshire, and Maine.
Regularity: Regularly occurring
Atlantic white-cedar grows in a narrow belt along the Atlantic and Gulf
coasts from southern Maine to northern Florida westward to southern
Mississippi [23,25]. It occurs no farther than 50 to 130 miles (80-210
km) inland . Vast stands occur in the Great Dismal Swamp of
Virginia and eastern North Carolina. Small isolated stands are more
typical in much of New Jersey, Georgia, and eastern Florida, but stands
are infrequent in Delaware and Maryland. The species is uncommon in
South Carolina but becomes more frequent in the Florida Panhandle and in
southern Alabama . At the western edge of its range in southern
Mississippi, Atlantic white-cedar grow in scattered relict stands .
Occurrence in North America
NH NJ NY NC RI SC VA
- The native range of Atlantic white-cedar.
Atlantic white-cedar is found most frequently in small dense stands in fresh water swamps and bogs, sometimes on sandy soils, but usually on acidic muck (peat). The species is absent or uncommon in areas where muck is underlain by clay or contains appreciable amounts of silt or clay. Habitats in southeastern New Jersey range from about 1 meter elevation, where the trees border the tidal marsh, to 43 meters in some inland stands. The species currently grows in at least one upland bog in northern New Jersey at an elevation of 457 meters.
Atlantic white-cedar is a small to medium-sized, columnar evergreen tree
which commonly reaches 40 to 60 feet (12-18 m) in height and 36 inches
(1 m) d.b.h. [16,25,40,45]. Individuals may occasionally reach 120 feet
(37 m) in height and 60 inches (152 cm) in diameter . Plants are
long-lived and can reach 1,000 years of age. However, stands rarely
survive more than 200 years .
The fibrous bark is narrowly fissured by long, flat, platelike ridges
[15,37]. Scalelike leaves are opposite and average 0.06 to 0.13 inch
(1.5-3.3 mm) in length [8,36]. Atlantic white-cedar is shallow-rooted
. On many swampy sites, roots are confined to the top 1 to 2 feet
(0.3-0.6 m) of peat, but on sites with lower water levels, roots may
extend considerably deeper .
Atlantic white-cedar is monoecious, with staminate and pistillate cones
occurring on separate shoots . Small, inconspicuous yellow or
reddish staminate flowers are borne singly at the tips of short
branchlets [15,16]. Each cone contains 5 to 15 small, rounded,
laterally winged seeds [15,25].
Habitat and Ecology
Atlantic white-cedar grows in bogs or swamps bordering mesotrophic
stagnant water, in swamp forests, bayheads, along stream channels,
behind stable dunes, and in moist depressions in pine flatwoods
[5,6,8,17,47]. In New England, it is often associated with glacial
kettles and outwash plains . Atlantic white-cedar grows in sun but
is also somewhat shade tolerant [9,45]. It is able to persist despite
periodic flooding . Plants can grow where standing water levels
reach 1 to 2 feet (0.3-0.6 m) during parts of the year and where sites
become partially desiccated during summer . Atlantic white-cedar
occurs in pure and mixed stands .
In addition to those species listed under DISTRIBUTION AND OCCURRENCE,
common overstory associates include eastern hemlock (Tsuga canadensis),
larch (Larix laricina), black spruce (Picea mariana), black gum (Nyssa
sylvatica), gray birch (Betula populifolia), and red maple (Acer rubrum)
in the northern portion of Atlantic white-cedar's range [19,21,32];
eastern white pine (Pinus strobus), yellow birch (Betula
alleghaniensis), and eastern hemlock (Tsuga canadensis) in some areas
; and pond pine (Pinus serotina), red maple, sweetbay magnolia
(Magnolia virginiana), and white bay (Magnolia glauca) in Virginia and
North Carolina [12,19,22]. Farther south, Atlantic white-cedar grows
with loblolly bay (Gordonia lasianthus), titi (Cliftonia monophylla),
water gum, and white bay [12,19].
Understory associates: Atlantic white-cedar stands are often
characterized by a dense, tangled, nearly impenetrable undergrowth .
Sweet pepperbush (Clethra alnifolia), swamp azalea (Rhododendron
viscosum), great rhododendron (Rhododendron maximum), highbush blueberry
(Vaccinium corymbosum), dangleberry (Gaylussacia frondosa), and
sweetbells leucothoe (Leucothoe racemosa) are common associates in the
northern portion of its range. Fetterbush lyonia (Lyonia lucida),
sweetbells leucothoe, highbush blueberry, pieris (Pieris nitida),
greenbrier (Smilax laurifolia), coast pepperbush (Cletha alnifolia),
redbay (Persea borbona), palmetto (Sabal palmetto), and sweet pepperbush
grow with Atlantic white-cedar in the South [4,25,49]. Lyonia (Lyonia
spp.), mountainlaurel (Kalmia spp.), titi (Cyrilla racemiflora), and
sweet pepperbush are common associates in shrub bogs .
Climate: Atlantic white-cedar grows under a warm, humid temperate to
subtropical climatic regime [5,25]. Annual precipitation averages 40 to
64 inches (102-163 cm) and temperatures range from winter lows of -36
degrees F (-38 degrees C) in Maine to 100 degrees F (38 degrees C)
during the summer in much of its range. Growing season ranges from 140
to more than 350 days [5,25].
Soils: Atlantic white-cedar is adapted to highly acidic soils that are
low in nutrients . It typically grows on muck or peat but also
occurs on some sandy soils . It is rare or absent where peat
contains significant amounts of silt or clay or where peat is underlain
by clay . Atlantic white-cedar reportedly thrives on water-logged
organic soils . Soils are generally acidic, with pH ranging from
3.5 to 5.5 .
Elevation: Atlantic white-cedar typically grows at low elevations along
the coast. Through most of the Northeast, it grows from sea level to
160 feet (50 m)  but can grow at elevations up to 1,500 feet (457 m)
in northern New Jersey .
Key Plant Community Associations
Atlantic white-cedar grows as an overstory dominant in peaty swamps. It
is listed as a dominant or indicator in the following community type
Area Classification Authority
VA general veg. cts Montague & Day 1980
southern U.S. swamp veg. cts Penfound 1952
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the terms: hardwood, swamp
45 Pitch pine
85 Slash pine - hardwood
97 Atlantic white-cedar
102 Baldcypress - tupelo
103 Water tupelo - swamp tupelo
104 Sweetbay - swamp tupelo - redbay
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES16 Oak - gum - cypress
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K113 Southern floodplain forest
Soils and Topography
As its range is restricted principally to coastal areas and to wet or swampy ground, Atlantic white-cedar usually grows at low elevation. In southeastern New Jersey these typically range from about 1 m (3 ft), where white-cedars border the tidal marsh, to 43 m (140 ft) in some inland stands. The species currently grows in at least one upland bog in northern New Jersey at an elevation of 457 m (1,500 ft).
Habitat & Distribution
Trees of Atlantic white-cedar in open stands start bearing seed at 4-5 years, although these seeds may be relatively low in viability; trees in dense stands begin cone production at 10-20 years. Fair to excellent seed crops are produced each year.
Germination occurs in a variety of light conditions, even in very low light intensity, but relatively open conditions are essential for good survival and growth of Atlantic white-cedar seedlings in competition with associates of shrubs and hardwoods (especially red maple, blackgum, sweetbay, and others). Establishment in nature usually occurs following disturbance of the canopy. Seedlings develop a very short taproot, and successful establishment requires not only adequate surface moisture for seed germination but also available moisture within reach of the shallow root systems. Suitable seedbeds include moist rotting wood, Sphagnum moss, muck, and moist mineral soil – these on hummocks where standing water is not present all year. Thick litter and slash are unfavorable for germination and establishment.
Increases in height slow after about 50 years and stop after 100 years; increases in diameter may continue at a relatively even rate up to 100 years. Stand age rarely exceeds 200 years, although some trees have apparently have reached 1000 years of age.
Associated Forest Cover
Many non-arborescent plants also grow with white-cedar. In a study of sixteen 0.04-hectare (0.1-acre) plots in southern New Jersey, the most common species of 25 shrubs associated with it were sweet pepperbush (Clethra alnifolia), swamp azalea (Rhododendron viscosum), highbush blueberry (Vaccinium corymbosum), dangleberry (Gaylussacia frondosa), and sweetbells leucothoe (Leucothoe racemosa). In a North Carolina study, fetterbush lyonia (Lyonia lucida) was the most common shrub, but sweetbells leucothoe, highbush blueberry, and sweet pepperbush were also present (6).
Diseases and Parasites
White-cedar on typical swamp sites is shallow rooted and subject to windthrow, especially in stands that have been opened by partial cuttings. Wind, often aided by snow or ice, is beneficial to hardwood understory development at times when white-cedar stands are gradually opened by the periodic windthrow or breakage of scattered trees; but extensive wind damage in one storm favors development of another white-cedar stand. Along the coast, salt water brought in by storm tides kills stands of various species, sometimes permitting a pure white-cedar stand (developing from seeds stored in the forest floor) to follow one composed largely of hardwoods (6).
Few fungi attack Atlantic white-cedar, and damage is not usually serious. Keithia chamaecyparissi and Lophodermium juniperinum attack white-cedar foliage; Gymnosporangium ellisii sometimes causes a broom-like development of branches; G. biseptatum occasionally causes a spindle-shaped swelling of stems or branches. Roots may be attacked by Armillaria mellea, Heterobasidion annosum, or Phaeolus schweinitzii. The latter and Fomitopsis cajanderi may attack heartwood, although the heartwood of Atlantic white-cedar is very resistant to decay (7).
White-cedar has no serious insect enemies, although larvae of the common bagworm (Thyridopteryx ephemeraeformis) may feed on its foliage.
Fire Management Considerations
Prescribed fire: Prescribed fire can be used to stimulate the
regeneration of Atlantic white-cedar and increase deer browse .
Slash fires can enhance germination of Atlantic white-cedar by clearing
the forest floor . Competing hardwoods can also be reduced or
eliminated if peat is heated enough to kill underground regenerative
Fuels/flammability: Logging slash left in Atlantic white-cedar types is
highly flammable and sites often "burn to the waters edge" .
Wildlife: Deer can seriously damage or kill postfire regeneration .
Lightning: Ward and Clewell  reported that in mixed
hardwood-Atlantic white-cedar forests of the Gulf Region, lightning is
apparently the primary natural factor determining the upper age and size
limit of Atlantic white-cedar.
Plant Response to Fire
Atlantic white-cedar readily establishes on burned sites through seed
stored on-site in peat or transported from adjacent stands [5,24].
Germination is generally favored when surface peat is too wet to burn
. Seeds often germinate in abundance and dense stands commonly
develop after a single fire [5,12,19]. Little and others  reported
the presence of 111,520 seedlings per acre (45,109/ha) 1 year after
fire, with numbers declining to 11,360 per acre (4,599/ha) by the second
Immediate Effect of Fire
Atlantic white-cedar is readily killed or damaged by fire [5,45], often
by even low-intensity fires . Crown fires will generally kill the
trees [25,35] and can eliminate an entire stand [12,26]. Large trees
not killed outright usually die gradually, beginning at the top .
Mature trees may occasionally survive low-intensity fires on wet sites
in parts of the South . On these sites, crown fires do not occur
"even under the impetus of strong winds and fires that have crowned in
adjacent associations" . Seedlings, however, are readily killed by
these low-intensity fires .
Wet swampy stands dominated by Atlantic white-cedar often serve as
natural fire breaks, but trees at the edge are usually commonly killed
before the fire is stopped [24,35]. Korstian  observed that in a
portion of the Great Dismal Swamp, all Atlantic white-cedars were killed
by a fire which occurred when the swamp was "full of water." However,
dry-season burns are typically most damaging to young growth and buried
seeds . Dry season burns often remove the upper layer of peat and
can eliminate all on-site seed [12,39].
Adult white-cedar trees are readily killed by fire, but successful
seedling establishment is largely dependent on fires of moderate
severity at relatively short intervals . Seeds stored in the peaty
soils often germinate in abundance after fire if the upper peat layers
are not destroyed . Atlantic white-cedar swamp forests in the
Southeast are typically produced by a low-frequency, moderate-severity
fire regime related to "marginally moist soil conditions" . In many
areas, increased fire suppression has led to the decline of Atlantic
white-cedar by promoting the growth of competing hardwoods such as red
maple, white bay, and black gum .
Changes in natural fire cycles have contributed to the decline of
Atlantic white-cedar in some areas. In many southeastern swamps, water
tables have been lowered for silvicultural and agricultural purposes,
which has increased the likelihood of dry season fires . Hardwood
forests of red maple, black gum, or water gum are often favored by
severe, dry season fires [4,19,34]. Atlantic white-cedar may persist
only on small hummocks of peat, near stumps, on moss-covered logs and on
rotten wood located above the general water level . In North
Carolina, South Carolina, and Virginia, moderate fires which occur
during the dry season, or within a few years of a previous fire, often
generate stands of pond pine [12,19]. Farther south, moderate or
frequent fires often produce stands of slash pine [19,34]. As fire
frequencies increase, Atlantic white-cedar declines and stands may be
replaced by shrub bogs as the fire-sensitive plants are killed and the
seed banks depleted . In the North, frequent fire tends to favor the
development of uniform stands of Atlantic white-cedar, but in the South,
mixed forests of white-cedar and hardwoods often develop .
In Florida and the Gulf Coast, wet seepage slopes burn infrequently
. Swamps in which Atlantic white-cedar occurs as a dominant
generally only burn after long droughts which increase the flammability
of peat [11,35]. At other times, these swampy areas serve as natural
fire breaks. Fires rarely begin in swampy Atlantic white-cedar stands.
Fire is particularly important in the establishment and persistence of
Atlantic white-cedar forests. Atlantic white-cedar is often capable of
colonizing moist open sites, and wet season fires which occur after
relatively long fire-free intervals tend to produce pure cedar stands
More info for the terms: climax, hardwood, shrub, swamp, tree
Atlantic white-cedar is long-lived but is often considered a subclimax
species . Paradoxically, although some form of disturbance is
generally necessary for establishment, disturbance can lead to
conversion to hardwood types . Even-aged stands of Atlantic
white-cedar often develop in response to fire, flooding, clearcutting,
or windthrow . This tree is described as "intermediate in tolerance
to shade" and is unable to grow through dense shrub thickets or a
hardwood overstory . In many areas, Atlantic white-cedar forests
are successional to evergreen bay forests when fire is excluded [4,5].
In the Great Dismal Swamp of Virginia and North Carolina, stands are
often replaced by red maple and black gum ; elsewhere in the South,
Atlantic white-cedar forests are replaced by climax stands of swamp red
bay (Tamala pubescens), white bay, and titi  or by sweetbay
magnolia, holly (Ilex myrtifolia), titi, and red bay (Persea pubescens)
in the absence of fire .
Once eliminated from a stand, Atlantic white-cedar will not regain
prominence until fire or other disturbance removes competing hardwoods
and creates a favorable seedbed. Plants reestablish by wind-dispersed
seed when buried seed reserves have been depleted and reestablishment is
often very slow. In some coastal areas, storm-borne saltwater can kill
hardwoods and allow Atlantic white-cedar to form nearly pure stands from
seed stored in the soil .
Seed: Atlantic white-cedar reproduces solely through an abundance of
light, winged seed [14,25]. In open stands, trees first produce seed at
3 to 5 years of age and often bear large crops from 4 years of age and
up [16,45]. In dense stands, seed production may not begin until plants
reach 10 to 20 years of age . As many as 9,000,000 seeds per acre
(22 million seeds/ha) may be produced annually .
Seed banking: Seed can remain viable for at least 1 to 2 years when
stored in the upper inch (2.5 cm) of peat [16,19]. Little and Garrett
 reported the presence of 260,000 to 1,100,000 viable seeds per acre
(642,000-2,718,000/ha) within the top inch (2.5 cm) of soil.
Germination: Germination of Atlantic white-cedar is often low due to
poor viability and embryo dormancy [16,25]. Stratification at 38 to 40
degrees F (3-4 degrees C) for 90 days may promote germination [2,25].
Delayed germination is common, and in laboratory tests up to 50 percent
of germination was delayed until the second year . Results of
specific germination tests were as follows :
stratification -days germ. test germ. capacity
warm cold day night days percent
0 0 86 F 68 F 60 ----
0 90 86 F 68 F 28 84
Seedling establishment: Open peat and adequate moisture are required
for good seedling establishment [25,34]. Rotting wood, sphagnum moss,
and muck or peat serve as favorable seedbeds . Thick litter and
dense slash can inhibit germination and subsequent establishment .
Adequate light is essential for good initial growth. Seedlings are
vulnerable to drought and flooding and often survive only on favorable
Vegetative regeneration: Heavy browsing and other types of injury can
cause plants to layer . As many as 15 stems may form from the same
root system as shoots develop from lateral branches or dormant stem buds
Growth Form (according to Raunkiær Life-form classification)
More info for the terms: phanerophyte, therophyte
Undisturbed State: Phanerophyte (mesophanerophyte)
Burned or Clipped State: Therophyte
off-site colonizer; seed carried by animals or water; postfire yr 1&2
Reaction to Competition
The small taproot formed during the first year is subsequently lost in the development of the strong superficial lateral roots. These are numerous but do not become large. Because of its characteristically shallow root system and weak root hold in the spongy organic soils, white-cedar cannot withstand severe winds, and many mature trees are felled in storms. Trees which have grown in dense stands on swamp peat never become windfirm, and consideration must be given this fact in planning the harvest of this species.
Life History and Behavior
Pollen is generally shed in March or April . Cones mature at the
end of the first growing season . Most seeds are shed during
October or November, but seeds continue to be shed throughout the winter
and into the early spring [16,37]. Citing the results of a single
study, Little and Garrett  reported that 39 percent of all seeds had
fallen by November 15, 60 percent had fallen by December 15, and 93
percent had been shed by March 1. Generalized flowering and fruiting
dates by geographic location are as follows:
Location Flowering Fruit ripe Authority
New England ---- July Seymour 1985 
NJ March Sept.-Oct. Harris 1974 
se U.S. March-April ---- Duncan & Duncan 1988 
s NJ April ---- Little & Garrett 1991 
Germination is epigeal, but delayed germination is common. Half the seeds sown in the fall in a nursery may not germinate until the second year. Consequently, stratification for 90 days at 4° C (40° F) before sowing has been recommended (12). Some of the seeds produced by mature stands remain viable for an unknown length of time when stored in the forest floor. In a New Jersey study of sites protected from additional seedfall for 1 year, the surface 2.5 cm (1.0 in) of forest floor was found to contain 642,000 to 2,718,000 viable seeds per hectare (260,000 to 1,100,000/acre), with nearly an equal amount in the 5-cm (2-in) muck layer underneath (6).
A fair amount of light is necessary for good germination of white-cedar seeds, but in one study, light intensity had to be less than 16 percent of full sunlight before germination was greatly reduced. Some germination occurred under a hardwood overstory where light intensity was only 1 percent of full sunlight (6).
Favorable moisture conditions are highly important for the germination and establishment of Atlantic white-cedar seedlings. In one experiment with artificial seeding, 49 percent of the seeds germinated in clearcut plots under typical swamp conditions, whereas in similar plots on drier but still poorly drained sites, only 16 percent germinated on exposed soil. As seedlings develop a very short taproot, the successful establishment of white-cedar requires not only adequate surface moisture for seed germination, but also available moisture within reach of the comparatively shallow root systems.
Suitable seedbeds include moist rotting wood, sphagnum moss, and muck, which are all common in many swamps, and moist mineral soil. A thick litter of pine needles, or the leaves of shrubs and hardwood trees, is unfavorable. On one poorly drained site with a thick litter, removing the litter from seed spots increased germination from less than 1 percent on untreated areas to 13 percent on the cleared spots. Stocking of spots was 3 and 81 percent.
Dense slash is extremely unfavorable for white-cedar establishment. In studies of natural reproduction on cutover areas, slash-free spots had at least 28 times as many seedlings as spots covered with dense slash (6).
The microrelief of swamps also greatly affects seedling establishment. Spots where water stands on the surface during much of the year are unfavorable for both seed germination and seedling survival. Suitable conditions are limited to the hummocks above the usual water table, but on these hummocks seedlings may die during dry periods from insufficient moisture. In general, the younger or smaller the seedlings are, the greater the mortality from either drowning or drought.
Relatively open conditions are essential for good survival and growth of white-cedar seedlings. At light intensities of 4 to 6 percent of full sunlight, as under mature white-cedar stands in New Jersey, seedlings survive for only 1 to 3 years. Partial cuttings that thin the overstory enable white-cedar reproduction to live longer, but not as long as competing hardwoods and shrubs. Under a light intensity of 77 percent, the initial growth of white-cedar seedlings was about twice that under a 16-percent intensity and almost 4 times that under a 2-percent intensity. Hence, only relatively open areas, such as abandoned cranberry bogs and clearcuttings, provide the conditions necessary for white-cedar seedlings to compete successfully with hardwood and shrub associates (6).
Open-grown Atlantic white-cedar seedlings may reach an average height of 6 cm (2.5 in) on unfavorable sites (such as sandy, poorly drained soils or cranberry bogs) and 15 to 25 cm (6 to 10 in) on favorable sites in the first year. In contrast, seedlings growing in swamps under heavy shade may reach a height of only 2.5 cm (1 in) and a taproot length of only 5 cm (2 in) during the same time.
On favorable open sites, seedlings add 0.2 to 0.3 m (0.6 to 0.9 ft) to their height during the second year, and about 0.3 m (1 ft) a year for a few years thereafter. Under these conditions, stems 3 m (10 ft) tall may be 7 or 8 years old in the South and about 10 years old in the Northeast. On less favorable sites, however, they may grow to heights of only 1.2 to 2.1 m (4 to 7 ft) in 15 years (6).
Seed Production and Dissemination
Natural reproduction in open stands starts bearing seed at 4 or 5 years, in dense stands at 10 to 20 years (6).
Cone production varies appreciably with tree size and crown class. Intermediate or crowded stems produce markedly fewer cones than open-grown or dominant trees of the same size. In one comparison of clumped and open-grown trees, the larger, mostly dominant trees in the clumps were fully as productive as open-grown trees of the same size; but the intermediate and smaller clumped trees were much less productive than their open-grown counterparts (4). Average numbers of cones per tree for some selected sizes were as follows:
Parent trees Clumped trees Open-grown trees no. of cones 1.5 to 2.1 m (5 to 7 ft) tall 4 52 8 to 10 cm (3 to 4 in) d.b.h. 1,074 2,891 13 to 18 cm (5 to 7 in) d.b.h. 4,540 4,218 White-cedar usually produces fair to excellent seed crops each year. Under one mature stand the catch in seed traps was 19.77 million seeds per hectare (8 million/acre) in 1 year and 22.24 million/ha (9 million/acre) the next year (6).
Natural seed dissemination begins in October in New Jersey and most of the seeds are released before the end of the winter. In one study, 39 percent of the crop fell by November 15, more than 60 percent by December 15, and 93 by March 1 (6).
Seed dispersal is influenced by weather conditions. In one series of observations, rain showers of 4 mm (0.16 in) or less caused only partial closing of some cones, whereas rains of 11 mm (0.45 in) or more caused all cones to close (6).
Wind distributes most of the white-cedar seeds, although some may be further scattered by floating on water. Probably because the seeds are so small and have relatively large wings, the rate of fall is slow- 0.02 m (0.6 ft) per second in still air. Calculations based on this rate of fall indicate that a wind of 8 km/h (5 mi/h) would carry most seeds from a 15-m (50-ft) tree about 183 m (600 ft). Records of seed traps around and under white-cedar stands showed that most of the seeds fall directly under the stands. Where surrounding vegetation was of comparable height, no seeds were trapped beyond 20 in (66 ft) from the stand's edge.
In a study of seed distribution from isolated trees, 60 percent of the seeds fell at a distance greater than the height of the tree, even though the catch per trap decreased greatly with increased distance. Because of prevailing winds during dry periods, 80 to 85 percent of the seed catch was on the east side of the source (6).
Flowering and Fruiting
The cones mature at the end of the first growing season. Full-grown cones are spherical, about 6 mm (0.2 in) in diameter and contain 5 to 15 winged seeds (6). Seeds are rounded, slightly compressed, about 3 mm (0. 1 in) long, and have winged margins about as broad as the seeds. There are about 1,014,000 seeds per kilogram (460,000/lb) (12).
Growth and Yield
Although white-cedar trees are relatively small, the basal area and volume of stands tend to be high because of the high stand density. On the basis of three 0.1 ha (0.25 acre) plots, one stand in Gates County, NC, had 68 m²/ha (294 ft²/acre) of basal area, 85 percent of which was white-cedar. Most of the trees of these plots were between 5 and 36 cm (2 and 14 in) in d.b.h. According to yield tables, basal areas may reach more than 69 m²/ha (300 ft²/acre). On areas with a site index at base age 50 years of 14 m (45 ft), 50-year-old stands may have 56 to 57 m²/ha (245 to 250 ft²/acre) of basal area and a total volume, including stumps and tops, of 322 m³/ha (4,600 ft³/acre). On a site index of 12 m (40 ft), a 60-year-old stand may have 4,200 stems per hectare (1,700/acre), yielding about 220 m³/ha (35 cords/acre) to an inside bark top diameter of 10 cm (4 in); a 70-year-old stand on a site index of 21 m (70 ft), 865 trees per hectare (350/acre) and 693 m³/ha (110 cords/acre). The yield to an inside-bark top diameter of 15 cm. (6 in) is 600 m³/ha (42,900 fbm/acre, International rule) at 60 years, and 1000 m³/ha (71,500 fbm/acre) at 100 years, both on a site index of 21 m (70 ft) (6).
In southern New England (lat. 41° to 42° N.), mature white-cedars reach heights of 12 to 18 m (40 to 60 ft) and a d.b.h. of about 41 cm (16 in), although some have grown to 122 cm (48 in). Optimum development-a maximum height of 37 m (120 ft) and a d.b.h. of 152 cm (60 in)-- apparently occurred in the Virginia-North Carolina section at lat. 34° to 37° N. The maximum sizes for white-cedar in Alabama (approximately lat. 31° N.) are somewhat less: 24 to 27 m (80 to 90 ft) high, with d.b.h. rarely more than 61 cm. (24 in) (6).
Potentially, white-cedar is a relatively long-lived species. According to one source, some trees have reached 1,000 years of age, although stand age rarely exceeds 200 years (6).
Molecular Biology and Genetics
Barcode data: Chamaecyparis thyoides
Statistics of barcoding coverage: Chamaecyparis thyoides
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Exploitation in the past has impacted this species primarily in terms of numbers of mature trees, but this situation has reversed in most places and the species is likely to recover. It has a very wide range and is present in most of its swamp forest habitat, including within many reserves. As a result it is assessed as Least Concern.
The nominate variety is not assessed separately as it is also Least Concern.
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
harvest has reduced its numbers . It may also serve as a "habitat
indicator" for several other rare plants . In parts of Florida, many
rare or endemic plants are associated with Atlantic white-cedar stands
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values. Atlantic white-cedar is considered rare in Georgia, Mississippi, Maine, Maryland, New York, New Hampshire, and Maine.
Timber harvest: Wetland drainage and heavy cutting has greatly reduced
Atlantic white-cedar, and in many areas harvested stands have been
maintained in an immature and degraded condition [24,25,46]. Harvesting
on a commercial scale is now generally limited to parts of North
Silviculture: Atlantic white-cedar often reestablishes in dense stands
after clearcutting . Following clearcutting in the Great Dismal
Swamp, seed stored in the upper 1 inch (2.5 cm) of peat germinated at a
rate of more than 3,574,840 per acre (8,640,000/ha) . The following
guidelines have been recommended for harvested Atlantic white-cedar
sites: (1) remove most of the slash, (2) allow periodic fires, (3)
control deer browsing if necessary, and (4) prevent the establishment of
competing vegetation [41,48].
Damage/disease: Atlantic white-cedar is resistant to disease and decay,
and has few insect pests . It is susceptible to windthrow and
storm-caused breakage .
Cultivars, improved and selected materials (and area of origin)
Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
Because of the shallow root system, trees of Atlantic white-cedar are extremely susceptible to windthrow, especially where they occur in permanently saturated sites and where stands have been opened by partial cuttings. Fungi and insects usually do not cause serious damage.
Relevance to Humans and Ecosystems
Uses: FIBER, Building materials/timber
Other uses and values
Atlantic white-cedar is attractive and hardy and is often planted as an
ornamental . More than 19 cultivars are now available [16,33].
Atlantic white-cedar is used locally as a Christmas tree in parts of the
Atlantic white-cedar provides cover for a variety of birds and mammals.
The yellow-throated warbler, prairie warbler, and hooded warbler nest
close to the ground in Atlantic white-cedar stands . Cavities
provide nesting areas for the pileated woodpecker .
Importance to Livestock and Wildlife
. In lowland sites of New Jersey, deer often browse plants during
the winter . Seedlings are especially favored  and may be
killed by intense deer use . Meadow mice occasionally browse the
stems and often girdle seedlings . Trees serve as territorial
marking posts for black bears in parts of the South .
Wood Products Value
lightweight, buoyant, and easily worked [25,37,46]. It is fragrant,
repels insects, and is resistant to decay [41,46]. Atlantic white-cedar
has been logged heavily since the Revolutionary War [19,24] for fuels,
ship-building, shingles, milled lumber, charcoal, household items,
barrels, pails, tubs, water tanks, and duck decoys [25,46].
The wood of Atlantic white-cedar is currently used for telephone poles,
posts, pilings, ties, siding, boat railing, decking, lawn furniture,
paneling, and ice cream buckets [16,46].
Value for rehabilitation of disturbed sites
disturbed wetland habitats. It has been planted at Tennessee Valley
Authority impoundments along shorelines within the fluctuation zone
Atlantic white-cedar can be propagated from seed. Cleaned seed averages
460,000 per pound (1,014,000/kg) . Atlantic white-cedar can also be
propagated from cuttings .
. Fruit is evidentally low in palatability for most birds and
The wood is light, soft, close-grained, and slightly fragrant. It is easily worked, resistant to decay, and shrinks and warps very little during seasoning. It has been used for shingles, posts, woodenware, and interior finishes, but primary current uses are for telephone poles, piling, ties, siding, and boat railing. Many cultivars of Atlantic white-cedar have been described (see Rehder 1949).
Heavy cutting for many commercial uses during this century has considerably reduced even the largest stands, but it is still considered a commercially important species in the major supply areas of southeastern Virginia, North Carolina, South Carolina, and northwestern Florida.
Cultivars have been selected for shape and needle color – they are useful for naturalizing in wet areas.
Chamaecyparis thyoides (Atlantic white cedar, Atlantic white cypress, or whitecedar falsecypress), is a species of Chamaecyparis, native to the Atlantic coast of North America from Maine south to Georgia, with a disjunct population on the Gulf of Mexico 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.
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.
- Chamaecyparis thyoides subsp. thyoides (Atlantic white cedar). Atlantic coast, Maine to Georgia. Leaves and cones usually glaucous blue-green; facial leaves flat, not ridged; cones 4–7 mm long. (Least concern)
- Chamaecyparis thyoides subsp. henryae (H.L.Li) E.Murray (Gulf white cedar; syn. Chamaecyparis thyoides subsp. henryae (H.L.Li) Little; Chamaecyparis henryae H.L.Li). Mexican Gulf coast, Florida to Mississippi. Leaves and cones always green, not glaucous; facial leaves with a longitudinal ridge; cones 6–9 mm long. (Near threatened)
Cultivation and uses
Chamaecyparis thyoides is of some importance in horticulture, with several cultivars of varying crown shape, growth rates and foliage color having been selected for garden planting. Named cultivars include 'Andelyensis' (dwarf, with dense foliage), 'Ericoides' (juvenile foliage), and 'Glauca' (strongly glaucous foliage). The wood is reported to endure moisture indefinitely; it has been used for fence-posts, ties and shingles.
|Wikimedia Commons has media related to Chamaecyparis thyoides.|
- Conifer Specialist Group (1998). Chamaecyparis thyoides. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006.
- Farjon, A. (2005). Monograph of Cupressaceae and Sciadopitys. Royal Botanic Gardens, Kew. ISBN 1-84246-068-4
- Germplasm Resources Information Network: Chamaecyparis thyoides
- Rushforth, K. (1987). Conifers. Helm ISBN 0-7470-2801-X.
- Peattie, Donald Culross. Trees You Want to Know. Whitman Publishing Company, Racine, Wisconsin, 1934 p31
A. J. Rehder (1949) listed, with bibliographic citations, 30 published varieties and forms best considered as cultivars.
Names and Taxonomy
Comments: John Kartesz (discussion with Larry Morse, 29Jul01) notes that he plans to treat Chamaecypris nootkatensis in the genus Cupressus in his next edition, but plans to keep C. thyoides and C. lawsoniana in Chamaecyparis.
Chamaecyparis thyoides (L.) B.S.P. . It is a member of the cypress
family (Cupressaceae) .
In some taxonomic treatments, two primarily geographic varieties of
Atlantic white-cedar have been delineated (var. henryae and var.
thyoides) [16,25]. However, most current taxonomic treatments no longer
recognize these varieties [18,25]. The existence of climatic races is
possible, although they have not yet been defined .
Chamaecyparis henryae Li
Chamaecyparis thyoides var. henryae (Li) Little