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V. 1

AGPiC-

_USRARY

3EGE!k'«3

!

*

_SWEETGUm)

an

american

wqoq

i

i

I

Swee(tgum

grows

throughout

most

pf

tie

eastern! United

States

and

sporadically

tHroudn-out

Mexico

and

Central

America.

The

wooa

is

moderately heavy,

even-j-extured,

and

i)

njachries

moderately

well.

It is

used

for

a

variety?

of

pur-poses, with

furniture,

plywood,

cdnfairprs,/and

pulp absorbing

the

most

vcjlume.

Growtrj

is

good,

but supplies

are

slowly diminishing

-because the

best

sites

are

being

taketi

out

of forestsJ

I)

4

FS-266

July

_r

1973

j

SWEETGUM

. . .

an American

wood

C.

B. Briscoe

1

DISTRIBUTION

Sweetgum

(

Liquidambar

styraciflua L.) occurs naturally in southwestern Connecticut, westward to

Missouri,

and

southward to central Florida

and

south-eastern Texas. It also grows in several states of

Mexico

and

in Guatemala, British Honduras,

Hon-duras, El Salvador,

and

Nicaragua (fig. 1).

Within that area, it can be found

from

sea level to

about 2,000 feet elevation in the United States

and

up

to nearly 7,000feetin CentralAmerica. It tolerates a wide variety of soils. Average annual

minimum

temperature varies

from

-10

degrees to above 60

degreesF.

Growing

seasonranges

from

about 150 days

in the northern United States to 365 days in parts of

Central America. Rainfall varies

from

less than

40

inches per year to

more

than 80. However,

where

rainfall is less than

40

inches, occurrence is generally

restricted to areas close to a water course,

swamp,

lake, or spring.

Best growth,

and

most commercialproduction, is on

moist, well-drained soils. Alluvial lands of the Ohio

and

Mississippi Rivers, valleys of

minor

rivers

and

stream bottoms oftheGulf andAtlantic coastalplains,

and

coves of the

Ozark

and

Cumberland

uplands

pro-vide excellent sites.

DESCRIPTION

AND

GROWTH

Mature

trees are 1.5 to 3 feet in diameter and 80

to 120 feet tall, depending on the site.

The

largest

known

sweetgum

in the United States is 6.3 feet in

diameter at breast height, is 125 feet tall,

and

has a

crown

spread of 100 feet. In the forest, the bole

may

be straight

and

cylindrical for fully two-thirds of the

total height.

Young

trees normally have a compact,

conical

crown

with excurrent branching (fig. 2), but

at maturity the

crown

often

becomes

open, round-to-1

Principal silviculurist, Southern Hardwoods Laboratory,

Southern Forest Experiment Station,

USDA

Forest Service,

Stoneville, Miss.

NOTE:

This publication supersedesunnumberedpublication

Sweetgum, issued 1954.

t

FS-521730

Figure 2.

—

Immature

sweetgum.

flat on top, and

some

of the branches

become

quite

heavy (fig. 3).

Leaves are alternate, simple, and deciduous; their star shape distinguishes

them

from

all other trees

native to the United States (fig. 4). Fall coloration

may

be yellow, red, or purple,

making

the tree very

attractive.

Twigs, especially of

young

trees, often bear corky

FS-262185

Figure 3.

—

Mature sweetgum.

ridges (fig. 5), adding to the tree's interest for land-scape planting.

Sweetgum

bark is gray

and

deeply furrowed, (fig. 6)

.

The

relatively inconspicuousflowers aremonoecious

and borne in earlyspring; production on open-grown

trees, or those in well-spaced plantations, begins as

early as age four. In natural stands, flowers are scarce or absent until age 20to 25.

The

fruit is a spiky ball (fig. 3)

which

persists

through

most

of the winter. It is

composed

of

many

small fruits, each with two long curved or spiny

pro-jections,

which

open in

autumn

to release one or two

small,

winged

seeds.

The winged

seeds mature in the early fall

and

are usually completely dispersed before winter.

Some

seed

is produced practically every year: abundant crops occur every 3 or 4 years.

Seedlings survive under moderate shade but

grow

well only

where

they receive a substantial

amount

of

light. Saplings

and

mature trees in

hardwood

stands arenormallya part ofthe upper

crown

canopy.

When

they fallbehind, growth reductionis marked, followed

by

stagnation

and

death.

Under

relatively open pine canopies, however,

sweetgum

often persists in such

abundance

as to reduce the growth

and

to prevent natural reproduction of the overstory pines.

The

species habitually grows in mixture with other

hardwoods and

pines. It is a key species in the north-ern red oak-mockernut hickory-sweetgum, pin

oak-sweetgum, sweetgum-yellow-poplar,

and

sweetgum-Nuttall oak-willow oak types. It is also an important

component

in 25 other types,ranging

from

the scarlet

oak to cabbage palmetto-slash pine.

On

old fields,

particularly clay or silt loams,

sweetgum

is often

preponderantor

may

even

form

purestands containing

up

to 40,000 board feet per acre. Small pure stands often arise as root sprouts

when

the

ground

is

physi-cally disturbed around recent stumps.

Such

trees

ap-pear to be as desirable and free

from

defect as those

of seedling origin, although there is

some

indication

that they are

more

susceptibleto drought damage.

Growth

varies greatly with conditions, but

may

at-tain 3 feet per year in

young

saplings of seedling origin or 5feet forsprouts. Diameter growth in stands

is

commonly

2 to 4 inches in 10years.

Natural regeneration is abundant

from

both seeds

and

sprouts

where

conditions are suitable.

Stumps

of

trees up to at least 50 years old will sprout,

and

root

sprouts will develop

from

trees that old or older.

Sweetgum

is very resistant to disease

and

insect

attacks, but it is quite susceptible to

damage by

fire.

Rodents clip

many

seedlings and are occasionally a

serious obstacle to plantation establishment.

COMMON

NAMES

Sweetgum

is the

common

name

preferred

by

the

USDA

Forest Service, but the species is also called

gum,

red

gum,

star-leaved

gum,

white

gum,

alligator

tree,

opossum

tree, and bilsted.

The

heartwood is

commonly

called red

gum

in the

trade.

Sapwood

is referred to as sap

gum,

or simply

gum,

in

common

with the tupelos (Nyssa aquatica L.,

N.sylvatica var. sylvaticaMarsh.,and N. sylvatica var.

biflora (Walt.) Sarg.). In Europe heartwood and

sapwood

are sometimes sold as satin walnut and hazel

pine, respectively.

SUPPLY

It is estimated that in 1920 the total supply

was

44.2 billion board feet, approximately 90 percent of

which

was

in the Mississippi Valley and the Gulf

and

South Atlantic coastal plains.

By

1945, the estimated

volume

had

dropped to 26 billionboard feet. In 1963

the estimate

was

virtuallythe

same

—

25.9billionboard

feet, 92percent of which

was

in the South.

In the

same

year, the

volume

in cubic feet

was

esti-mated

as 10 billion, with 25percent in trees less than

10 inches in diameter

and

only 10 percent in trees

largerthan 19 inches.

As

indicated earlier, however, growth is

good and

the gradual reduction in overall

volume

is not the

result ofoverharvesting, but ofconversion ofso

much

of the best

sweetgum

forest to reservoirs and

row

crops.

PRODUCTION

The

production of

sweetgum

lumber increased

from

4million boardfeet in 1869 to a peak of 1.13 billion

board feet in 1926.

Volume

slowly climbed after the 1930's nadir of 202 million to a post-World

War

II

peak of 1.08 billion board feet, fell again in the

1950's,

and

was

onlya little over300million in 1960.

CHARACTERISTICS

AND

PROPERTIES

The

sapwood

is wide

and

white to pinkish.

The

faint-to-marked bluish tinge often seen is theresult of

fungus infection.

Heartwood

varies through shades of

red, reddishbrown,

and

brown, and

may

includevery

attractive grain figure.

Annual

rings are definite but inconspicuous.

The

wood

is diffuse porous, and the texture is uniform.

Interlocked grain is

common

and

contributes to both

the difficulty in seasoning thelumber and to a

ribbon-stripe figure.

The

wood

ismoderatelyheavy (34

pounds

per cubic foot at 12 percent moisture content) and moderately hard

and

stiff. It is above average for southern

hard-woods

in turning, boring,

and

steaming properties.

It is intermediate for planing, shaping, bending,

split-ting,

and

for nail-

and

screw-holding ability.

The

heartwood is non-durable, difficult to treat

and

does not glue readily.

Fiber length averages about 1.8 millimeters. It

varies significiantly between geographic areas, but even

more

between individual trees within a single forest.

It is readily pulped

by

sulfate

and

semichemical

processes, yielding fine paper, liner board, or rayon,

according to theprocess used.

When

the bark is scraped away, thetree secretes a

clear, balsamic oleoresin which tastes like turpentine

and

is

known

as storax or styrax. Weathering turns

the resin to a fragrant, chocolate-brown

gum

which

is

called

sweetgum

and is often

chewed

by

children.

The

commercial storax market is normally supplied

from

the oriental species, L. orientalis, but

when

the

supply is interrupted,

gum

from

the

American

species

is freely substituted.

PRINCIPAL USES

Sweetgum

is used primarily for lumber, veneer,

plywood, pulpwood,

and

slack cooperage.

The

lumber

goes into boxes

and

crates, general usage, dimension

stock, and is remanufactured into furniture parts

and

fixtures. Veneer usage follows the

same

pattern, except

that a greater proportion goes into containers

and

prefabricated products.

Plywood

goesmostly into

con-tainers, although interior construction

and

furniture-making

also use large quantities.

Briefly,

gum

is widely available, easily adaptable

and

is used for a variety ofpurposes.

Storax is used in medicinal

and

pharmaceutical

preparations, especially skin

and

mucous-membrane

salves.Itis alsousedforadhesives, incense, perfuming

powders

and

soaps, as a fixative in heavy perfumes,

and to flavor tobacco.

The

spiky-ball fruit is often painted silver or gold,

adornedwith sequins orglitter,

and

usedfor

Christmas-tree decorations.

REFERENCES

American

Forestry Association.

1971.

AFA's

social register of bigtrees.

Amer.

For.

77(1) :25-31.

Gill,

Thomas

G.,

and

Robert B. Phelps.

1969.

Wood

usedin manufacturingindustries, 1965.

USDA

For. Serv. Stat. Bull. 440, 101 p., illus.

Hair, D.,

and

B. Spada.

1970.

Hardwood

timber resources of the United

States. Unasylva 24(4):29-32.

Hunter, A. G.,

and

J. F. Goggans.

1969. Variation of fiber length of

sweetgum

in

Alabama.

TAPPI

52(10) :1952-54.

Johnson, RobertL.

1964. Coppice regeneration of sweetgum. J. For.

62(1) :34-35.

Kormanik,

P. P.,

and

C. L. Brown.

1969.Origin

and

developmentofepicormic branches

in sweetgum.

USDA

For. Serv. Res. Pap. SE-54.

17 p.

Little, Elbert L., Jr.

1971. Atlas of United Statestrees. Vol. I

—

Conifers

and

important hardwoods. U.S. Dep.Agric. Misc. Publ. 1146, 9 p., illus. (Maps: Base

Map

1-W,

1-E, 2-N;

Maps

1-94, Conifers;

Maps

95-200,

Hardwoods)

.

May, M.

N.

1958. Pulping possibilities of certain southern

bottomlandhardwoods.In

Management

of

bottom-land forests, p. 77-89. La. State Univ. 7th

Annu.

For.

Symp.

Proa, Baton Rouge, La.

Putnam, John

A., George

M.

Furnival,

and

J. S.

Mc-Knight.

1960.

Management and

inventory of southern

hard-woods.

USDA

Agric.

Handb.

181, 102 p., illus.

Schery, Robert

W.

1952. Plants for

man.

229 p. Prentice-Hall, Inc..

Englewood

Cliffs, N.J.

Society of

American

Foresters.

1954. Forest cover types of

North America

(exclu-sive of

Mexico

). 67 _p. Washington, D.C.

USDA

Forest Service.

1948. Woody-plant seed manual. U.S. Dep. Agric. Misc. Publ. 654, 416 p., illus.

USDA

Forest Service.

1949.

Hardwoods

of the South. 16 p. For. Prod. Lab., Madison, Wise.

USDA

Forest Service.

1965.

Timber

trends in the United States.

USDA

For. Serv. Resur. Rep. 17, 235 p., illus.

USDA

ForestService.

1965. Silvics of forest trees of the United States.

USDA

Agric.

Handb.

271, 762 p., illus.

Vines, Robert A.

1960. Trees, shrubs,

and

woody

vines of the

South-west. 1104 p., illus. Univ. Texas Press, Austin.

White, L. C.

1958.

Methods

of thinning

sweetgum

stands. In

Management

of bottomland forests, p. 42-45. La. State Univ. 7th

Annu.

For.

Symp.

Proa, Baton Rouge, La.

!r U.S.

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PRINTING

OFFICE:

1973

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