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Toxicodendron radicans — poison-ivy

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Facts

Poison ivy, although reviled for its capacity to raise a nasty, itchy rash, should also be admired for its versatility. It takes on many forms, from small seedlings to shrubs, to high-climbing vines. With its shiny, variably toothed leaves displayed in groups of three, it is easy to recognize. When ripe, the white fruits are a favorite food of many migrant and game birds, as well as white-tailed deer. The seeds are adapted for sprouting after digestion softens the seed coat. Poison ivy sap has been used to make indelible ink. Field experiments have shown that poison ivy is tolerant of being inundated by wastewater, and could potentially be used to treat sewage.

Habitat

Anthropogenic (man-made or disturbed habitats), forests

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
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Growth form
the plant is a liana (i.e., a woody plant with a vine-like growth form)
Leaf type
the leaf blade is compound (i.e., made up of two or more discrete 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
  • the edge of the leaf blade has no teeth or lobes
  • 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 stalk
the leaves have leaf stalks
Fruit type (general)
the fruit is fleshy
Bark texture
the bark of an adult plant is thin and smooth
Twig winter color
  • brown
  • gray
  • white
Bud scale number
there are no scales on the winter buds
Show all characteristics

  • Buds or leaf scars

    Bud position relative to scar
    the winter bud has a leaf scar just below it
    Bud scale number
    there are no scales on the winter buds
    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
    Winter bud distribution
    the winter buds are distributed fairly evenly along the twig
    Winter bud scale hairs
    NA
    Winter bud scales
    the winter bud is naked (not covered with scales)
    Winter bud stalks
    • the winter buds have no stalks
    • the winter buds have short stalks

  • Flowers

    Anther color
    the anthers show no hint of a pink, reddish or purplish tint
    Carpels fused
    the carpels are fused to one another
    Enlarged sterile flowers
    there are no enlarged sterile flowers on the plant
    Flower petal color
    yellow or green
    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 position
    • the inflorescences grow on older branches
    • the inflorescences grow on the twigs
    Inflorescence type
    the inflorescence is a panicle (branched with the individual flowers on stalks)
    Number of pistils
    1
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal fusion
    the perianth parts are separate
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal cilia (Ilex)
    NA
    Sepal tip glands
    there are no glands at the tips of the sepal lobes
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Stamen number
    5
    Stamens fused
    the stamens are not fused to one another

  • Fruits or seeds

    Berry color
    • some other color
    • white
    • yellow
    Fruit tissue origin
    there are no flower parts that form part of the fruit
    Fruit type (general)
    the fruit is fleshy
    Fruit type (specific)
    the fruit is a drupe (fleshy, with a firm inner ovary wall that encloses a single seed)
    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 liana (i.e., a woody plant with a vine-like growth form)

  • Leaves

    Hairs on underside of leaf blade
    • the underside of the leaf has hairs on it
    • the underside of the leaf has no hairs
    Hairs on upper side of leaf blade
    • the upper side of the leaf is fuzzy or hairy
    • 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 rounded
    • the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
    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 lobes, or it has both teeth and lobes
    • the edge of the leaf blade has no teeth or lobes
    • 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
    the hairs on the leaf blade are different from the choices given
    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 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 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 edge of the leaf blade is entire (has no teeth or lobes)
    • the leaf blade margin is crenate (with rounded teeth) or crenulate (with tiny, rounded teeth)
    • the leaf blade margin is serrate (with forward-pointing) or dentate (with outward-pointing) with medium-sized to coarse teeth
    • the leaf blade margin is undulate (wavy), but does not have teeth
    Leaf teeth hairs (Carya)
    NA
    Leaf type
    the leaf blade is compound (i.e., made up of two or more discrete leaflets
    Leaves per node
    there is one leaf per node along the stem
    Specific leaf type
    the leaf is compound, with three leaflets
    Stipules
    there are no stipules on the plant, or they fall off as the leaf expands

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • forests
    • man-made or disturbed habitats

  • 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 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
    Twig papillae (Vaccinium species only)
    NA
    Twig scales
    there are no scales on the twig surface
    Twig winter color
    • brown
    • gray
    • white
    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.

Maine
unranked (S-rank: SNR)

ssp. negundo

Vermont
historical (S-rank: SH)

ssp. radicans

Massachusetts
widespread (S-rank: S5)

Subspecies and varieties

Toxicodendron radicans (L.) Kuntze ssp. radicans is known from CT, MA, ME, NH, RI, VT. T. radicans ssp. negundo (Greene) Gillis is known from VT, and is of conservation concern.

From Flora Novae Angliae dichotomous key

1.  Toxicodendron radicans (L.) Kuntze NC

poison-ivy.  1a. Toxicodendron aboriginum Greene; T. negundo Greene; T. radicans (L.) Kuntze var. negundo (Greene) Reveal;  1b. Rhus radicans L.; R. toxicodendron L. var. radicans (L.) Torr.; Toxicodendron vulgare P. Mill. • CT, MA, ME, NH, RI, VT; extending into the northern states primarily along the coastal plain and the Lake Champlain valley. Roadsides, forests, coastal areas.

1a.  Leaflets softly pubescent across abaxial surface; petioles pubescent; drupes usually glabrous … 1a. T. radicans ssp. negundo (Greene) Gillis

1b.  Leaflets glabrous on the abaxial surface except along main veins and tufts of hairs in the axils of the veins; petioles glabrous; drupes pubescent, scabrous, or papillose 
 … 1b. T. radicans ssp. radicans


Subspecies radicans is known from CT, MA, ME, NH, RI, VT. Subspecies negundo is known from VT and is of conservation concern.

Native to North America?

Yes

Sometimes confused with

Toxicodendron rydbergii:
plants straggling shrubs without aerial roots and with fruits that lack hairs (vs. T. radicans, which are plants high-climbing lianas to sprawling shrubs with aerial roots produced along the stem and fruits with sparse hairs).

Synonyms

  • Rhus radicans L.
  • Rhus toxicodendron L. var. radicans (L.) Torr.
  • Toxicodendron vulgare P. Mill.

Family

Anacardiaceae

Genus

Toxicodendron