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Carpinus caroliniana — American hornbeam

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Facts

American hornbeam is a small tree of bottomland understories. It gets another common name, muscle tree, from the sinewy texture of its gray, fluted, smooth trunk. It is also called ironwood for its very dense timber. Squirrels, rabbits, and beaver eat the seeds, wood, and bark. The small nuts are edible, but seldom used by humans. Being exceptionally dense and difficult to work, the wood is primarily used to fashion tough handles for striking implements like hammers.

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
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • 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 teeth
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
25–120 mm
Leaf blade width
10–50 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 thin and smooth
Twig winter color
  • brown
  • gray
  • 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
    Leaf scar arrangement
    there is one leaf scar per node on the stem or twig
    Superposed buds
    there are no superposed buds on the branch
    Terminal bud
    there is no terminal bud on the branch
    Winter bud scale hairs
    the winter bud scales have no hairs on them
    Winter bud scales
    the winter bud is perulate (partially or completely covered with one or more scales)
    Winter bud shape
    the winter buds are ovoid (egg-shaped)
    Winter bud stalks
    the winter buds have no stalks
  • 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 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
    • the flower lacks sepals and petals
    Petal appearance
    NA
    Petal fusion
    NA
    Sepal cilia (Ilex)
    NA
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Stamen number
    • 3
    • 4
    • 5
    • 6
    Stamen position relative to petals
    NA
    Stamens fused
    the stamens are not fused to one another
  • 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)
    • the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)
    Nut with spines (Fagaceae)
    NA
    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 underside of leaf blade
    the underside of the leaf has hairs on it
    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 cordate (heart-shaped, with rounded lobes)
    • the base of the leaf blade is rounded
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    Leaf blade bloom
    the underside of the leaf has no noticeable bloom
    Leaf blade edges
    the edge of the leaf blade has teeth
    Leaf blade edges (Acer)
    NA
    Leaf blade flatness
    the leaf is flat (planar) at the edges
    Leaf blade hairs
    at least some of the hairs on the leaf blade have glands at their tips
    Leaf blade length
    25–120 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)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    Leaf blade texture
    the leaf blade is herbaceous (has a leafy texture)
    Leaf blade translucent dots
    there are no translucent dots on the leaf blade
    Leaf blade vein pattern
    the main veins of the leaf blade are pinnate (the secondary veins branch off at intervals from the main central vein) and non-arcuate (not arched towards the leaf tip)
    Leaf blade veins
    the leaf blade has one main vein running from the base toward the tip
    Leaf blade width
    10–50 mm
    Leaf duration
    the leaves drop off in winter (or they wither but persist on the plant)
    Leaf form
    the plant is broad-leaved (with broadly flattened leaf blades)
    Leaf lobe tips (Quercus)
    NA
    Leaf midrib glands
    the midrib of the leaf blade lacks glands on the upper surface
    Leaf stalk
    the leaves have leaf stalks
    Leaf stalk attachment to leaf
    the petiole attaches at the basal margin of the leaf blade
    Leaf stalk nectaries
    there are no nectaries on the leaf stalk
    Leaf stalk shape
    the leaf stalk is not flattened
    Leaf teeth
    the leaf blade margin has teeth, which themselves have smaller teeth on them
    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
    Stipules
    the plant has stipules
  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • 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 thin and smooth
    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
    Lenticels on twigs
    there are clearly lenticels on the twigs
    Pith shape
    the outline of the pith in a twig is roughly round
    Pith type
    the pith inside the twig is solid, completely filled with spongy tissue
    Twig bloom
    there is no bloom on the twig
    Twig hairs
    • the twigs have few or no hairs on them
    • the twigs have hairs, but the hairs do not have glands
    Twig papillae (Vaccinium species only)
    NA
    Twig scales
    there are no scales on the twig surface
    Twig winter color
    • brown
    • gray
    • 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

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

In New England

Distribution

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

Conservation status

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

ssp. virginiana

Maine
unranked (S-rank: SNR)
Massachusetts
widespread (S-rank: S5)

Subspecies and varieties

Our subspecies is Carpinus caroliniana Walt. ssp. virginiana (Marsh.) Furlow.

From Flora Novae Angliae dichotomous key

1.  Carpinus caroliniana Walt. ssp. virginiana (Marsh.) Furlow N

American hornbeam. Carpinus betulus L. var. virginiana Marsh.; C. caroliniana Walt. var. virginiana (Marsh.) Fern.; C. virginiana (Marsh.) Sudworth • CT, MA, ME, NH, RI, VT. River banks, seepage swamps, riparian and deciduous forests.

Native to North America?

Yes

Synonyms

  • Carpinus betulus L. var. virginiana Mash.
  • Carpinus caroliniana var. virginiana (Marsh.) Fern.
  • Carpinus virginiana (Marsh.) Sudworth

Family

Betulaceae

Genus

Carpinus