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- Dioscorea polystachya
Dioscorea polystachya — Chinese yam
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Facts
Chinese yam, native to east Asia, is planted as a garden ornamental in North America. It is occasionally found in waste areas, compost piles or fields in Connecticut, Massachusetts and Vermont. The stems twine in a clockwise direction.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Vermont
- 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)
- the leaf blade is triangular, with the stalk or attachment point on one of the sides
- Leaf blade length
- 30–90 mm
- Flower petal color
-
- green to brown
- white
- yellow
- Flower petal length
- 13–20 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 is a spike (a long unbranched stem with flowers along it that lack stalks)
- the inflorescence is in the form of a compact cluster of flowers
- 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
- 12–20 mm
-
Clonal plantlets
- Axillary bulblets
- there are bulblets in some axils
-
Flowers
- Anther attachment
- the anther is attached by its base to the filament
- 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 bracts
- there are bracts associated with the flower
- Flower number
- 1–8
- Flower orientation
- the flowers point upward or spread or curve outward
- Flower petal color
-
- green to brown
- white
- yellow
- Flower petal length
- 13–20 mm
- Flower shape
-
- the flower is bell-shaped
- the flower is cup-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
- the axis of the inflorescence has no hairs on it
- Inflorescence length
- 20–100 mm
- Inflorescence type
-
- the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
- the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
- the inflorescence is in the form of a compact cluster of flowers
- Length of flower stalk
- At least 0 mm
- Length of peduncle
- 0 mm
- Marks on petals
- the petals have spots or streaks on them
- 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
- 1.3–2 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
- the stamens are fused to one another at or near their bases
- 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
- 12–20 mm
- 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
- 12–20 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 one or more swollen storage organs underground, such as bulbs, tubers or corms
-
Leaves
- Hairs on underside of leaf blade
- 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 truncate (ends abruptly in a more or less straight line as though cut off)
- Leaf blade bloom
- the underside of the leaf blade has no 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
- 30–90 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)
- the leaf blade is triangular, with the stalk or attachment point on one of the sides
- 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 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
- 30–110 mm
- Leaf stalk length
- 20–30 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
- New England state
-
- Connecticut
- Massachusetts
- Rhode Island
- Vermont
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
-
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 is nearly or completely hairless
Wetland status
Not classified
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- 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
- not applicable (S-rank: SNA)
From Flora Novae Angliae dichotomous key
1. Dioscorea polystachya Turcz. E
Chinese yam. Dioscorea batatas R. Decr. • CT, MA, RI, VT. Waste places, compost heaps, fields. The name Dioscorea oppositifolia L. has been used for this species, but that name correctly refers to a plant that is native to India and not found in New England (Raz 2002).
Native to North America?
No
Sometimes confused with
- Dioscorea villosa:
- leaves with unlobed blades, lacking bulbils in the axils, and alternate in the distal portion of the stem, and plants with rhizomes (vs. D. polystachya, with 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).