Quercus palustris Muenchh. - Pin Oak, Swamp Oak, Water Oak,

Native , Common

By Steven D. Glenn

Not peer reviewed

Last Modified 01/25/2013

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Quercus palustris

Common Names

Pin Oak, Swamp Oak, Water Oak,

Field Identification

Medium-sized to large deciduous tree with alternate, simple, lobed leaves; buds clustered near twig ends; catkin-like flowers in spring followed by acorns in the fall. Distinctive branching habit with - upper 1/3 branches ascending, middle horizontal, lower 1/3 declining.

Medicinal uses

Disclaimer: The information provided here is for reference and historical use. We do not recommend nor do we condone the use of this species for medicinal purposes without first consulting a physician.

Used by Native Americans to treat intestinal pains. (Moerman, 1998)

Other uses

Oak-mast surveys may help wildlife agencies better understand dynamics of fall harvests and may be useful in harvest management models that attempt to stabilize fall harvest rates of game animals (Norman, 2003).

Tannins derived from oaks have been used historically to tan animal hides into leather. (Burrows & Tyrl, 2001)

The wood was used by Native Americans to make pins and pegs. (Moerman, 1998)

Poisonous Properties

Oak leaves, buds, bark, and acorns contain tannins which have varying degrees of toxicity in different animals. Although oak foliage and acorns provide valuable food for many wildlife species and even some livestock, oak toxicosis, a urinary and digestive tract disease can occur when some animals are forced to subsist on oaks exclusively for several days. Poisoning is rare in humans due to the large amounts needed to ingest to cause symptoms. (Burrows & Tyrl, 2001)


Dryads (or "tree spirits") are nymphs associated with Greek mythology which live near, or in, trees. Dryads are born bonded to a specific tree, originally, in the Indo-European Celtic-Druidic culture, an oak tree. Drys in Greek signifies 'oak,' from an Indo-European root *derew(o)- 'tree' or 'wood.'

In a nationwide vote hosted by the National Arbor Day Foundation in 2001, the oak was selected as America's National Tree.


Quercus palustris Muenchh., Hausvat. 5: 253. 1770.
Quercus rubra var. dissecta Lam., Encycl. Meth. Bot. 1: 720. 1785.
Quercus rubra ramosissima Marsh., Arbust. Am. 122. 1785.
TYPE: unknown


HABIT Perennial, deciduous (often marcescent), phanerophytic, tree, diclinous and monoecious, 20-25 m tall.

STEMS Main stems ascending or erect, round. Bark brown or gray, tightly irregularly fissured with scaly ridges, not exfoliating. Branches- upper 1/3 ascending, middle horizontal, lower 1/3 declining. Twigs brown to reddish-brown or gray, fluted-terete, 2-5 mm in diameter, smooth and lenticellate, glabrous. Pith white, 5- pointed, continuous, nodal diaphragm absent. Sap translucent. For an anatomical study of the xylem see (Tillson & Muller, 1942). For an anatomical study of seedling roots see (Carpenter & Guard, 1954).

BUDS Terminal and axillary present, clustered at twig apices and scattered along stem, glabrous or slightly hairy on distal half only. Terminal bud ovoid, blunt; axillary buds ovoid, blunt. Bud scales dark brown or brown (distal margins darker-colored), imbricate, glabrous or with short and unbranched appressed brown or light brown hairs, sparsely distributed. Bud scale scars encircling the twig. Leaf scars crescent, half-round. Vascular bundle scars numerous, scattered.

LEAVES Alternate, simple, (appearing pseudo-opposite or pseudo-whorled at twig apices), crowded toward stem apex or spaced somewhat evenly along and divergent from stem. Stipules lateral, free from the petiole, linear, caducous. Petiole adaxially flattened, 1-5 cm long, glabrous (rarely with scattered minute fasciculate hairs). For an anatomical study of the petiole abscission region see Hoshaw & Guard, 1949. Leaf blades: abaxial surface light green, adaxial surface green, elliptic or oblong or obovate, bilaterally symmetric, 6-17 cm long, 5.5-15 cm wide, chartaceous, base acute or cuneate or truncate, margins somewhat symmetrically 2-3(4) lobed per side 1/2 - 7/8 distance to the midvein with rounded sinuses and acute, aristate apices; apex acute and aristate. Abaxial surface obscurely papillose and glabrous except for tufts of fasciculate erect to spreading brown hairs, distributed in the main vein axils. Adaxial surface glabrous. Other types of hairs (multi-cellular bulbous, unicellular solitary) present but difficult to discern without high magnification, see Hardin, 1979a;Thompson & Mohlenbrock, 1979; and for an overview of the phenology and the variability and density of hairs due to ecological factors and hybridization see Hardin, 1979b.

FEMALE INFLORESCENCES Coetaneous, spike consisting of a single flower (sometimes 2-3), in axils of current year leaves, subsessile initially, often becoming short-pedunculate in fruit, surrounded by a cupule which is persistent, accrescent, and indurate in fruit (acorn cap). There has been debate over the years regarding the true ontogenetic nature of the cupule. Originally thought to be an involucre of bracts, recent research suggests that the cupule is a complex partial inflorescence derived from stem tissue, see Abbe, 1974;Brett, 1964;Foreman, 1966;MacDonald, 1979;Fey & Endress, 1983. Each cupule subtended by 3 minute, caducous bracteoles.

FEMALE FLOWERS Perianth of one whorl, minute, fragrance absent. Calyx urceolate, of fused sepals. Carpels 3. Locules 3, each containing 2 ovules. Styles 3, each with 1 stigma. Ovary inferior. Placentation axile.

MALE INFLORESCENCES Coetaneous, compound, solitary or fascicled spikes; pendant, catkin-like; in leaf axils of previous year. Rachis moderately covered with brown to white hairs; elongating and glabrescent with age; with 1 subsessile or sessile flower per node, each flower subtended by a small, sessile caducous bracteole.

MALE FLOWERS Perianth of one whorl, fragrance absent. Calyx actinomorphic, campanulate, of fused sepals. Sepal lobes 5-6, broadly oval to ovate with brown to white hairs moderately dense along margins. Stamens 4-5, exserted. Anthers glabrous, basifixed, opening along the long axis. Filaments free, 1mm long, straight, glabrous. For a review of pollen morphology see Solomon, 1983a.

FRUITS Acorn (glans (Spjut, 1994)) (calybium (Kaul, 1985)) sessile to short-pedunculate; maturation biennial. Acorn ovoid-subglobose, 1.2-1.5 cm long, comprised of 2 parts- a. the acetabuliform cup (cupule), enclosing 1/4 of the base of the nut; and b. the nut, 1-seeded by abortion (for a hypothesis that the first ovule fertilized suppresses the normal development of the others see Mogensen, 1975. The pericarp is reported to have a thick coating of wax (Bonner, 1968). Cupule exterior composed of imbricate, moderately appressed scales sparsely to moderately covered with brown tomentum. Nut olive-green to brown, ovoid-subglobose, with large light-colored circular cupule scar at base and apiculate at the distal end; minutely laterally striate; initially with minute short and unbranched appressed brown to light brown hairs, sparsely or moderately densely distributed throughout, glabrescent. One study found a size range of 0.47-2.00 cubic cm with a mean of 0.90 cubic cm and a correlation between smaller acorn size with increasing latitude see Aizen & Woodcock, 1992.

SEEDS Embryo with two large fleshy cotyledons, endosperm lacking. (Young & Young, 1992).


Usually occurring in moist to mesic poorly drained substrates of woods, swamps, and roadsides; very intolerant of shade.


Indigenous to eastern North America.

United States -- AR, CT, DC, DE, IA, IL, IN, KS, KY, MA, MD, MI, MO, NC, NJ, NY, OH, OK, PA, RI, TN, VA, WI, WV

Canada -- ON

New York Metropolitan Region -- Native throughout the metropolitan region.

Rarity Status

Global Heritage Rank -- G5

Connecticut -- Not listed

New Jersey -- Not listed

New York -- Not listed

Species Biology

April [week 4] - May [week 3]
August [week 1] - October [week 4]
Small predators of acorns facilitate dispersal by dropping undamaged nuts and failing to recover cached nuts. These include Sciurus carolinensis (gray squirrel), Sciurus niger (fox squirrel), Glaucomys volans (Southern Flying Squirrel), Tamias striatus (eastern chipmunk), Peromyscus leucopus (white-footed mouse), Peromyscus maniculatus (deer mouse), Quiscalus quiscula (common grackle) and Cyanocita cristata (blue jay). (Ivan & Swihart, 2000) (Smith, 1972) (Briggs & Smith, 1989) (Wolff, 1996) (Bosema, 1979) (Darley-Hill & Johnson, 1981) (Johnson & Webb, 1989) (Johnson, et al., 1993) (Vaughan, 1991). In addition, one study found that many predators preferred the basal end of the acorn and consumed only 30-60% of the cotyledon. A chemical analyses of acorns from two species revealed that the concentration of protein-precipitable phenolics (primarily tannins) was 12.5% (Q. phellos) and 84.2% (Q. laevis) higher in the apical portion of the seeds where the embryo is located, suggesting that many acorn consumers consistently eat only a portion of the cotyledon of several species of acorns and thereby permit embryo survival. (Steele, et al., 1993) .

 Probably included in the diet of the grey fox (Urocyon cinereoargenteus) (Scott, 1955), eastern wild turkeys (Meleagris gallopavo silvestris) (Norman, 2003), and white-tailed deer (Odocoileus virginianus) (Bryant, et al., 1996).
Water absorbed mainly through the vascular opening in the cup scar; the thick coating of wax on the pericarp may explain the high tolerance to submergence (Bonner, 1968) .

General rules for collecting and storing acorns: 1. Collect acorns before they lose much water. 2. Ensure acorns are fully hydrated, soak in clean tap water overnight before placing them in storage. 3. Surface dry the acorns just before depositing them in storage to reduce mold growth. 4. Place acorns into cold storage as soon after collection as is possible. (Connor, 2004)