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Pin Oak - Quercus palustris
Also commonly called swamp oak, water oak, and swamp Spanish oak.
Fagaceae -- Beech family |
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Pin Oak has an unruly, dense branching habit |
Pin oak (Quercus palustris), also called swamp oak, water
oak, and swamp Spanish oak, is a fast-growing, moderately
large tree found on bottom lands or moist uplands, often on
poorly drained clay soils. Best development is in the Ohio
Valley. The wood is hard and heavy and is used in general
construction and for firewood. Pin oak transplants well and
is tolerant of the many stresses of the urban environment,
so has become a favored tree for streets and landscapes.
Native Range - Pin oak grows from southwestern New England
west to extreme southern Ontario, southern Michigan,
northern Illinois, and Iowa; south to Missouri, eastern
Kansas, and northeastern Oklahoma; then east to central
Arkansas, Tennessee, central North Carolina, and Virginia.
Pin oak grows primarily on level or nearly level, poorly
drained alluvial floodplain and river bottom soils with high
clay content (order Entisols). Pin oak is usually found on
sites that flood intermittently during the dormant season
but do not ordinarily flood during the growing season. It
does not grow on the lowest, most poorly drained sites that
may be covered with standing water through much of the
growing season. It does grow extensively on poorly drained
upland "pin oak flats" on the glacial till plains of
southwestern Ohio, southern Illinois and Indiana, and
northern Missouri (order Alfisols). Because of the level
topography and presence of a claypan in the soil, these
sites tend to be excessively wet in the winter and spring. |
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Pin oak is a major species in only
one forest cover type, Pin Oak-Sweetgum (Society of
American Foresters Type 65), which is found on bottom
lands and some upland sites throughout the central
portion of the pin oak range (8). Associated species in
this type include red maple (Acer rubrum), American elm
(Ulmus americana), black tupelo (Nyssa sylvatica), swamp
white oak (Quercus bicolor), willow oak (Q. phellos),
overcup oak (Q. lyrata), bur oak (Q. macrocarpa), green
ash (Fraxinus pennsylvanica), Nuttall oak (Quercus
nuttallii), swamp chestnut oak (Q. michauxii), and
shellbark (Carya laciniosa) and shagbark (C. ovata)
hickories. Pin oak and sweetgum (Liquidambar
styraciflua) vary in their relative proportions in this
cover type, and large areas of almost pure pin oak occur
on the "pin oak flats" of the upland glacial till plains
or in the bottom lands of the lower Ohio and central
Mississippi River valleys. Pin oak is
an associated species in Silver Maple-American Elm (Type
62) in the bottom lands along the Ohio, Wabash,
Mississippi, and Missouri Rivers; a variant of this
type, silver maple-American elm-pin oak-sweetgum, is
found along major streams in southern Illinois and
Indiana. Pin oak also occurs in Black Ash-American
Elm-Red Maple (Type 39) in poorly drained bottom lands
in northern Ohio and Indiana along with silver maple
(Acer saccharinum), swamp white oak, sycamore (Platanus
occidentalis), black tupelo, and eastern cottonwood
(Populus deltoides). |
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This pin oak started from acorn 22 years ago |
Pin Oak bark showing old pruning wounds |
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Acorn Weevil, Curculio sp. |
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Flowering and Fruiting- Pin oak
is monoecious; flowers appear at about the time the
leaves develop in the spring. Staminate flowers are
borne on aments that develop from buds formed in the
leaf axils of the previous year, and pistillate
flowers are borne on short stalks from the axils of
current-year leaves. Pollination is by wind. Fruit
is an acorn (nut) that matures at the end of the
second growing season after flowering. Acorns are
dispersed from September to early December.
Seed Production and Dissemination- Pin oak stands
begin producing seed at about age 20, but open-grown
trees may begin at ages as young as 15 years. During
a 14-year period, production of mature acorns in 32-
to 46- year-old pin oak stands in southeastern
Missouri averaged 210,300/ha (85,100/acre) but
varied yearly from 13,300 to 492,700/ha (5,400 to
99,400/acre). Poor acorn crops occurred at 3- to
4-year intervals. Insect infestation rates varied
inversely with crop size and, over all years,
averaged 26 percent. Pin oak acorns are dispersed by
squirrels, mice, blue jays, and woodpeckers.
Pin oak acorns submerged in cold water as long as 6
months were not damaged. This tolerance may be
partly due to a thick, waxy coating on the pericarp
that impedes water absorption. The acorns require
stratification of 30 to 45 days at 0° to 5° C (32°
to 41° F) to break dormancy, and germination of
sound, stratified acorns averages about 68 percent .
Damaging Agents- although pin oak
is very tolerant of dormantseason flooding, it is
much less tolerant of growing-season flooding and
trees may be injured or killed by intermittent
growing-season flooding over several successive
years. The trees can usually survive one growing
season of continuous flooding but will be killed by
continuous flooding over 2 or 3 consecutive years
(2,4,10,22). Pin oak is rated as "intermediately
tolerant" to growing season flooding, along with
such species as sugar maple (Acer saccharum), river
birch (Betula nigra), southern red oak (Quercus
falcata), and Shumard oak (Q. shumardii); it is less
tolerant than red maple, silver maple, sweetgum,
sycamore, swamp white oak, and American elm
(tolerant) and eastern cottonwood, green ash, and
black willow (very tolerant) (28,29). Dormant-season
flooding for 20 years in a greentree reservoir in
southeastern Missouri did not appear to damage pin
oak trees, but did reduce stand basal area growth by
10 percent. However, in this same area approximately
5 years later (i.e., after 25 years of flooding),
many, of these trees had developed bole swellings at
and just above the average flood water level. These
swellings caused longitudinal fissures in the bark
up to 10 cm (4 in) wide, thereby exposing the bole
xylem to decay organisms. The cause of this
phenomenon is unknown, but it appears to be
associated with the continuous dormant-season
flooding, because pin oaks in adjacent areas subject
only to intermittent natural flooding were not
similarly affected.
The bark of pin oak is relatively thin and the
species is therefore especially susceptible to
damage by fire and the decay associated with fire
wounds (12,22). Pin oak is subject to most of the
diseases of oaks including oak wilt (Ceratocystis
fagacearum) and is particularly susceptible to a
leaf blister fungus (Taphrina caerulescens), a
shoot-blight and twig canker fungus (Dothiorella
quercina), and pin oak blight (Endothia gyrosa)
(12). Pin oak is also host to many of the common
oak-feeding insects including many defoliators, wood
borers, gall wasps, and acorn weevils. Pin oak is
classified as a "most preferred" host for gypsy moth
(Lymantria dispar), and is also especially
susceptible to the obscure scale (Melanaspis
obscura), oak leaftier (Croesia semipurpurana), pin
oak sawfly (Caliroa lineata), scarlet oak sawfly (C.
quercuscoccineae), the sawfly Calinoa petiolata, the
forest tent caterpillar (Malacosoma disstria), a
leafroller (Argyrotaenia quercifoliana), the homed
oak gall wasp (Callirhytis cornigera), and the gouty
oak gall wasp (C. quercuspunctata). Thousands of
acres of pin oak stands in southern Illinois have
been severely damaged over the past 25 years by
outbreaks of the horned oak gall wasp and the forest
tent caterpillar. |
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Pin Oak Fall Foliage |
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