Dioscorea villosa L.

wild yam

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Wild yam is native to most of the eastern half of the United States, but only reaches north as far as southern New England, including Connecticut, Massachusetts and Rhode Island. This is a highly polymorphic species, showing variation in many characters across habitats, geography, and even within a single plant.

Habitat

Floodplain (river or stream floodplains), forests, wetland margins (edges of wetlands)

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Massachusetts
  • Rhode Island
Leaf arrangement
  • alternate: there is one leaf per node along the stem
  • opposite: there are two leaves per node along the stem
  • whorled: there are three or more leaves per node along the stem
Leaf blade shape
  • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
Leaf blade length
30–130 mm
Flower petal color
  • green to brown
  • white
Flower petal length
0.5–2 mm
Petal fusion
  • the perianth parts are fused to form a tube, cup, or bell shape
  • the perianth parts are separate
Inflorescence type
  • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
  • the inflorescence has only one flower on it
  • the inflorescence is a dichasial cyme (an axis with a terminal flower, below it a pair of branches, each with a terminal flower, these branches may in turn have a pair of branches and so on)
  • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
Ovary position
the ovary is below the point of petal and/or sepal attachment
Fruit type (specific)
the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
Fruit length
10–30 mm
Show All Characteristics
  • Clonal plantlets
    Axillary bulblets
    there are no bulblets being produced in axils
  • Flowers
    Anther attachment
    the anther is attached by its base to the filament
    Anther color
    the anthers show no hint of a pink, reddish or purplish tint
    Bulblets replace flowers
    there are no bulblets where the flowers are located
    Carpels fused
    the carpels are fused (the number of carpels equals the number of locules)
    Flower bract length
    1–3 mm
    Flower bracts
    there are bracts associated with the flower
    Flower number
    1–18
    Flower orientation
    • the flowers curve or droop downwards
    • the flowers point upward or spread or curve outward
    Flower petal color
    • green to brown
    • white
    Flower petal length
    0.5–2 mm
    Flower shape
    • the flower has a funnel-shaped corolla tube
    • the flower is bell-shaped
    • the flower is flattened or platter-shaped
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Form of style
    the style is branched above the base
    Fringed petal edges
    the petals are not fringed
    Hairs on flower stalk
    the flower stalk has no hairs on it
    Inflorescence hair glands
    NA
    Inflorescence length
    20–300 mm
    Inflorescence type
    • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
    • the inflorescence has only one flower on it
    • the inflorescence is a dichasial cyme (an axis with a terminal flower, below it a pair of branches, each with a terminal flower, these branches may in turn have a pair of branches and so on)
    • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Length of flower stalk
    At least 0 mm
    Length of peduncle
    20–300 mm
    Marks on petals
    there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    3
    Number of pistils
    3
    Number of sepals and/or petals
    there are six petals, sepals or tepals in the flower
    Number of styles
    3
    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
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal base
    the petal narrows gradually or does not narrow at the base
    Petal fusion
    • the perianth parts are fused to form a tube, cup, or bell shape
    • the perianth parts are separate
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal nectaries
    there are nectaries at the petal bases
    Sepal appearance
    the sepals resemble petals in color and texture
    Sepal length
    0.5–2 mm
    Sepal orientation
    • the sepals are pressed against the plant, or jutting stiffly upward
    • the sepals are slightly curved outwards from the plant
    Sepals fused only to sepals
    • the sepals are fused to each other (often along with the petals in monocots), at least near their bases
    • the sepals are separate from one another
    Spathe
    the plant does not have a spathe
    Spathe form
    NA
    Spathe length
    0 mm
    Stamen number
    6
    Stamen position relative to petals
    NA
    Stamen types
    the stamens within a cycle are distinctly of two types
    Stamens fused outwards
    the stamens are fused to the petals or tepals at or near their bases
    Style petal-like
    the style is not broad and flattened like a petal
    Tepals
    the petals and sepals are similar in size and color
  • Fruits or seeds
    Berry color
    NA
    Capsule ridges
    there are three ribs or wings on the capsule
    Fruit compartments
    there are three locules in the fruit
    Fruit length
    10–30 mm
    Fruit stalk orientation
    the fruits point upward or spread or curve outward
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
    Fruit width
    10–35 mm
    Other markings on berry
    NA
  • Glands or sap
    Sap
    the sap is clear and watery
  • Growth form
    Lifespan
    the plant lives more than two years
    Root septa
    the roots do not have transverse septa
    Underground organs
    the plant has a rhizome (a horizontal underground stem with roots growing from it)
  • Leaves
    Hairs on underside of leaf blade
    • the underside of the leaf is fuzzy or hairy
    • the underside of the leaf is not hairy, or has very few hairs
    Hairs on upper side of leaf blade
    the upper side of the leaf is not hairy, or has very few hairs
    Leaf arrangement
    • alternate: there is one leaf per node along the stem
    • opposite: there are two leaves per node along the stem
    • whorled: there are three or more leaves per node along the stem
    Leaf blade basal lobes
    the leaf blades are lobed at their bases
    Leaf blade base
    the leaf has a distinct leaf stalk (petiole)
    Leaf blade base shape
    • The base of the leaf blade is cordate (heart-shaped, with rounded lobes) or sagittate (arrow-shaped, with pointed, backward-facing lobes)
    • 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 bloom
    the underside of the leaf blade has a noticeable waxy or powdery bloom
    Leaf blade cross-section
    the leaf blade is more or less flat in cross-section
    Leaf blade faces
    both surfaces of the leaf blade are exposed
    Leaf blade form
    Fully-formed (i.e., expanded), +/- green leaf blades are found somewhere on the plant
    Leaf blade length
    30–130 mm
    Leaf blade orientation
    the upper surface of the leaf blade faces the stem of the plant
    Leaf blade shape
    • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf blade tip
    • the tip of the leaf blade is acuminate (tapers to a long, thin point)
    • the tip of the leaf blade is acute (sharply pointed)
    • the tip of the leaf blade is caudate (has a very long tail-like projection ending in a point)
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    20–130 mm
    Leaf stalk length
    30–140 mm
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
    Leaflet number
    0
    Stipule twining
    NA
    Stipules
    there are no stipules on this plant
  • Place
    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Massachusetts
    • Rhode Island
    Specific habitat
    • edges of wetlands
    • forests
    • river or stream floodplains
  • Scent
    Plant odor
    the leaves have no particular smell
  • Stem, shoot, branch
    Flowering stem growth form
    the flowering stem trails along the ground or on other vegetation, or floats in the water
    Flowering stem leaves
    there is at least one fully-formed leaf on the flowering stem
    Stem hairs
    • the stem has hairs on it
    • the stem is nearly or completely hairless

Wetland Status

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

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Massachusetts
unranked (S-rank: SNR), #NAME? (code: #NAME?)
Rhode Island
rare (S-rank: S2), concern (uncertain) (code: C*)

Native to North America?

Yes

Sometimes Confused With

Dioscorea polystachya:
leaves with 3- to 5-lobed blades, with bulbils in the axils, and usually opposite in the distal portion of the stem, and plants tuberous (vs. D. villosa, with leaves with unlobed blades, lacking bulbils in the axils, and alternate in the distal portion of the stem, and plants with rhizomes).

Synonyms

  • Dioscorea hirticaulis Bartlett
  • Dioscorea villosa L. var. hirticaulis (Bartlett) Ahles

Family

Dioscoreaceae

Genus

Dioscorea

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Information from Dichotomous Key of Flora Novae Angliae

2.  Dioscorea villosa L. N

wild yam. Dioscorea hirticaulis Bartlett; D. villosa L. var. hirticaulis (Bartlett) Ahles 
• CT, MA, RI. Riparian and lacustrine forests, wetland borders. The report of this species 
from VT by Angelo and Boufford (2000) is based on a specimen (at NEBC) that was 
later annotated to Dioscorea polystachya.