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Quercus palustris — pin oak

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Facts

Pin oak is a fast-growing, primarily southern and mid-western species that reaches the northeastern edge of its range in New England; Maine populations are considered introduced. It gets its common name from its numerous, thin twigs. It resembles red oak (Q. rubra), but its leaves have much deeper concavities (sinuses) between the lobes, and its acorns are much smaller; also, the tips of its winter buds are blunt, whereas those of red oak are sharply pointed. Caterpillars of the common gray hairstreak butterfly (Strymon melinus) eat the leaves of pin oak.

Habitat

Floodplain (river or stream floodplains), forests, shores of rivers or lakes, swamps

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • Rhode Island
  • Vermont
Growth form
the plant is a tree
Leaf type
the leaf blade is simple (i.e., lobed or unlobed but not separated into leaflets)
Leaves per node
there is one leaf per node along the stem
Leaf blade edges
the edge of the leaf blade has lobes, or it has both teeth and lobes
Leaf duration
the leaves drop off in winter (or they wither but persist on the plant)
armature on plant
the plant does not have spines, prickles, or thorns
Leaf blade length
50–160 mm
Leaf blade width
50–120 mm
Leaf stalk
the leaves have leaf stalks
Fruit type (general)
the fruit is dry but does not split open when ripe
Bark texture
the bark of an adult plant is ridged or plated
Twig winter color
  • brown
  • red
Bud scale number
there are three or more scales on the winter bud, and they overlap like shingles, with one edge covered and the other edge exposed
Show all characteristics

  • Buds or leaf scars

    Bud scale number
    there are three or more scales on the winter bud, and they overlap like shingles, with one edge covered and the other edge exposed
    Bud scar shape (Fraxinus)
    NA
    Collateral buds
    there are no collateral buds on the sides of the branches
    Superposed buds
    there are no superposed buds on the branch

  • Flowers

    Carpels fused
    the carpels are fused to one another
    Enlarged sterile flowers
    there are no enlarged sterile flowers on the plant
    Flower petal color
    NA
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Hairs on ovary (Amelanchier)
    NA
    Hypanthium present
    the flower does not have a hypanthium
    Inflorescence type
    • the inflorescence has only one flower on it
    • the inflorescence is an ament (catkin; slender, usually pendulous inflorescence with crowded unisexual flowers)
    Number of pistils
    1
    Ovary position
    the ovary is below the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes only one cycle of petals or sepals
    Petal appearance
    NA
    Petal fusion
    NA
    Sepal cilia (Ilex)
    NA
    Stamen number
    • 1 or 2
    • 10
    • 11
    • 12
    • 3
    • 4
    • 5
    • 6
    • 7
    • 8
    • 9

  • Fruits or seeds

    Berry color
    NA
    Fruit tissue origin
    there are no flower parts that form part of the fruit
    Fruit type (general)
    the fruit is dry but does not split open when ripe
    Fruit type (specific)
    the fruit is a nut (dry and indehiscent, with a hard wall, usually containing only one seed and usually subtended by an involucre)
    Wings on fruit
    there are no wings on the fruit

  • Glands or sap

    Sap color
    the sap is clear and watery
    Stalked glands on fruit (Rosa)
    NA

  • Growth form

    Growth form
    the plant is a tree

  • Leaves

    Hairs on upper side of leaf blade
    the upper side of the leaf is not hairy, or has very few hairs
    Leaf blade base shape
    • the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
    • the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
    Leaf blade edges
    the edge of the leaf blade has lobes, or it has both teeth and lobes
    Leaf blade edges (Acer)
    NA
    Leaf blade flatness
    the leaf is flat (planar) at the edges
    Leaf blade hairs
    • NA
    • the hairs on the leaf blade are different from the choices given
    Leaf blade length
    50–160 mm
    Leaf blade scales
    there are no scales on the leaf blades
    Leaf blade shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is oblong (rectangular but with rounded ends)
    Leaf blade texture
    the leaf blade is coriaceous (has a firm, leathery texture)
    Leaf blade translucent dots
    there are no translucent dots on the leaf blade
    Leaf blade width
    50–120 mm
    Leaf duration
    the leaves drop off in winter (or they wither but persist on the plant)
    Leaf lobe tips (Quercus)
    the lobes of the leaf blade are tipped with small bristles
    Leaf midrib glands
    the midrib of the leaf blade lacks glands on the upper surface
    Leaf stalk
    the leaves have leaf stalks
    Leaf stalk nectaries
    there are no nectaries on the leaf stalk
    Leaf teeth
    the leaf blade margin is undulate (wavy), but does not have teeth
    Leaf teeth hairs (Carya)
    NA
    Leaf type
    the leaf blade is simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaves per node
    there is one leaf per node along the stem
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets

  • Place

    Habitat
    wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • Rhode Island
    • Vermont
    Specific habitat
    • forests
    • river or stream floodplains
    • shores of rivers or lakes
    • swamps

  • Scent

    Plant odor
    the plant does not have much of an odor, or it has an unpleasant or repellant odor

  • Stem, shoot, branch

    Aerial roots
    the plant has no aerial roots
    Bark texture
    the bark of an adult plant is ridged or plated
    Branch brittleness (willows only)
    NA
    Branch cross-section
    the branch is circular in cross-section, or it has five or more sides, so that there are no sharp angles
    First-year cane (Rubus)
    NA
    Pith shape
    the ouline of the pith in a twig is roughly star-shaped, with several points or arms radiating from the center
    Twig papillae (Vaccinium species only)
    NA
    Twig winter color
    • brown
    • red
    Wings on branch
    the branch does not have wings on it
    armature on plant
    the plant does not have spines, prickles, or thorns

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
absent
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Massachusetts
fairly widespread (S-rank: S4)

From Flora Novae Angliae dichotomous key

10.  Quercus palustris Muenchh. n

pin oak. CT, MA, ME, RI, VT. Swamps, riparian forests, pond shores. This species is native to southern New England but introduced (as a planting) in ME and VT.

10×16. Quercus palustris × Quercus velutina → Quercus ×‌vaga Palmer & Steyermark is a very rare oak hybrid known from MA. It tends to show the bark and growth habit of Q. palustris along with the involucral bracts of Q. velutina. The leaf blades also show tufts of pubescence in the axils of the primary lateral veins.

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Quercus coccinea:
terminal winter bud pubescent in the apical half, noticeably 5-angled in cross-section, carpellate involucre concealing 1/3 to 1/3 of the nut, and nut with 1 or more concentric rings of fine pits near the apex (vs. Q. palustris, with the terminal winter bud glabrous or with a few hairs near the apex, terete to obscurely angled in cross-section, carpellate involucre concealing 1/5 to 1/3 of the nut, and nut lacking rings of fine pits near apex).
Quercus rubra:
sinuses of leaf blade generally extending less than 1/2 the distance from the tips of the lobes to the midrib, nut 15–30 mm long, and terminal winter buds sharply pointed at apex, 4–7 mm long (vs. Q. palustris, with sinuses of leaf blade generally extending more than 1/2 the distance from the tips of the lobes to the midrib, nut 10–16 mm long, and terminal winter buds bluntly pointed at apex, 3–5 mm long).

Family

Fagaceae

Genus

Quercus