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Amphicarpaea bracteata — American hog-peanut

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Facts

American hog-peanut has two forms of flowers, with one type occuring at the top of the plant, and the other underground. The underground flowers are self-fertilizing and don't need to be visited by a pollinator to produce seeds. Needless to say, underground seeds don't often disperse far from the parent plant. However, they are edible, and were widely eaten by Native Americans.

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
Flower petal color
  • blue to purple
  • white
Leaf type
the leaves are compound (made up of two or more discrete leaflets
Leaf arrangement
alternate: there is one leaf per node along the stem
Leaf blade edges
the edge of the leaf blade is entire (has no teeth or lobes)
Flower symmetry
there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
Number of sepals, petals or tepals
  • there are five petals, sepals, or tepals in the flower
  • there are four petals, sepals, or tepals in the flower
Fusion of sepals and petals
  • both the petals and sepals are separate and not fused
  • the petals or the sepals are fused into a cup or tube
Stamen number
10
Fruit type (general)
the fruit is dry and splits open when ripe
Fruit length
15–40 mm
Show all characteristics

  • Clonal plantlets

    Bulbils
    the plant does not appear to have bulbils
    Bulblets replace flowers
    there are no bulblets where the flowers are located

  • Flowers

    Anther opening
    the anthers have narrow slits or furrows that run lengthwise along the anthers
    Anther spurs
    the anthers do not have spurs on them
    Carpels fused
    • NA
    • the carpel is solitary or (if 2 or more) the carpels are not fused to one another
    Cleistogamous flowers
    • the plant has some cleistogamous flower
    • there are no cleistogamous flowers on the plan
    Corolla morphology
    NA
    Corolla palate
    no
    Corona lobe length
    0 mm
    Epicalyx
    the flower does not have an epicalyx
    Epicalyx number of parts
    0
    Filament surface
    the filament is smooth, with no hairs or scales
    Flower description
    the flower has a superior ovary and a hypanthium
    Flower length
    12–18 mm
    Flower number
    1–17
    Flower orientation
    the flower bends downwards or hangs downwards
    Flower petal color
    • blue to purple
    • white
    Flower reproductive parts
    the flower has both pollen- and seed-producing parts
    Flower symmetry
    there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowers sunken into stem
    no
    Form of style
    the style is knob-like at the tip, and unbranched
    Fused stamen clusters
    there are two clusters of fused stamens
    Fusion of sepals and petals
    • both the petals and sepals are separate and not fused
    • the petals or the sepals are fused into a cup or tube
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower has a hypanthium
    Inflorescence one-sided
    • the flowers are all or nearly all arrayed on one side of the inflorescence axis or branches of the inflorescence
    • the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
    Inner tepals (Rumex)
    NA
    Interior flower disk
    the flower has an interior disc
    Length of flower stalk
    1.5–5 mm
    Length of peduncle
    10–60 mm
    Marks on petals
    there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of branches in umbel
    0
    Number of carpels
    1
    Number of pistils
    1
    Number of sepals, petals or tepals
    • there are five petals, sepals, or tepals in the flower
    • there are four petals, sepals, or tepals in the flower
    Number of styles
    1
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Perianth shape
    NA
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal and sepal colors
    • blue to purple
    • white
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal base
    the petal narrows abruptly at the base
    Petal folds or pleats
    • the petals of the flower do not have folds or plaits
    • the petals of the flower have folds or plaits on them
    Petal hairs (Viola)
    NA
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal length
    10–15 mm
    Petal length relative to sepals
    the petals are longer than the sepals
    Petal number
    5
    Petal shape
    • the petal outline is elliptic (shaped like an ellipse; widest near the middle and tapering at both ends)
    • the petal outline is obovate (roughly egg-shaped, but with the widest point above the middle of the leaf blade)
    Petal tips (Cuscuta)
    NA
    Raceme attachment (Veronica)
    NA
    Reproductive system
    all the flowers have both carpels and stamens (synoecious)
    Scales inside corolla
    no
    Sepal and petal color
    the sepals are different from the petals
    Sepal appearance
    the sepals are green or brown, and leaf-like in texture
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal color
    • blue to purple
    • green to brown
    • pink to red
    • white
    Sepal length
    5–6 mm
    Sepal number
    4–5
    Sepal relative length
    the sepal lobes are shorter than the fused portion
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Spur length
    0 mm
    Spur number
    NA
    Stamen morphology
    the stamens within each cycle are the same
    Stamen number
    10
    Stamens fused
    the stamens are attached to one another at or near their bases
    Staminodes
    there are no staminodes on the flower
    Stigma position
    the stigmas are positioned at the tip of the style
    Style petal-like
    the styles are not petal-like
    Umbel flower reproductive parts
    NA
    Upper lip of bilabiate corolla
    NA

  • Fruits or seeds

    Achene relative orientation
    NA
    Achene shape
    NA
    Achene surface (Polygonum)
    NA
    Achene type
    NA
    Berry color
    NA
    Capsule color (Viola)
    NA
    Capsule ribs
    NA
    Capsule splitting
    • NA
    • the capsule splits by two main valves, teeth or pores
    Carpel beak length
    0 mm
    Fruit (pyxis) dehiscence
    NA
    Fruit cross-section
    the fruit is at least somewhat flattened
    Fruit features (Brassicaceae)
    NA
    Fruit length
    15–40 mm
    Fruit locules
    one
    Fruit shape
    • the fruit is flat or strongly compressed
    • the fruit is obloid (longer than wide and with rounded ends)
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a legume (a fruit that splits into two valves, but only has a single carpel; think of a pea pod)
    Fruit width
    8–10 mm
    Hair type on fruit
    the hairs on the fruits are simple (not branched), don’t have glands, and are not woolly
    Hairs on fruit
    the fruits have hairs on them
    Legumes (Fabaceae)
    the legume has valves that split elastically and coil after they split
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit has a stipe
    Placenta arrangement
    the plant has parietal placentation, where ovules develop on the wall or slight outgrowths of the wall forming broken partitions within a compound ovary
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Seed number
    3–4
    Septum in fruit (Brassicaceae)
    NA
    Wings on fruit
    the fruit does not have wings on it
    prickles on fruits
    the fruits do not have thorn-like defensive structures

  • Glands or sap

    Glands on leaf blade
    the leaf blades do not have glandular dots or scales
    Sap
    the sap is clear and watery
    Sap color
    the sap is clear

  • Growth form

    Growth form
    the plant is a vine (it cannot support its own weight)
    Lifespan
    the plant lives only a single year or less
    Parasitism
    the plant is not parasitic
    Plant color
    the leaves or young stems of the plant are green
    Spines on plant
    the plant has no spines
    Underground organs
    there are only slender roots on the plant

  • Leaves

    Bracteole edges
    NA
    Bracteole length
    0 mm
    Bracteole number (Apiaceae)
    0
    Bracteole shape
    NA
    Bracteoles
    there are no bracteoles on the plant
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    20–80 mm
    Final leaf segment length to width ratio (compound lvs only)
    1–1.5
    Final leaf segment width (compound lvs only)
    anything
    Floral bracts
    the flower has one or more bracts associated with it
    Flower bract length
    2–5 mm
    Hairs on underside of leaf
    the underside of the leaf is fuzzy or hairy
    Hairs on upper side of leaf
    the upper side of the leaf is fuzzy or hairy
    Hooked hairs on underside of leaf
    no
    Inflated hairs on leaf
    the leaf blade does not have inflated hairs on it
    Leaf arrangement
    alternate: there is one leaf per node along the stem
    Leaf blade base
    the leaf has a distinct leaf stalk (petiole)
    Leaf blade base shape
    the base of the leaf blade is rounded
    Leaf blade base symmetry
    • the leaf blade base is asymmetrical
    • the leaf blade base is symmetrical
    Leaf blade bloom
    • the underside of the leaf has no noticeable bloom
    • there is a noticeable powdery or waxy bloom on the underside of the leaf
    Leaf blade edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade flatness
    the leaf is flat (planar) at the edges
    Leaf blade hairs
    the leaf blade has simple hairs with no glands, and not tangled or wooly
    Leaf blade primary vein pattern
    the secondary veins branch off at intervals from the primary vein
    Leaf blade shape
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    • the leaf blade is rhombic (roughly diamond-shaped)
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf blade texture
    the leaf blade is herbaceous (has a leafy texture)
    Leaf blade vein pattern
    the major veins of the leaf blade branch, but do not rejoin
    Leaf duration
    the leaves drop off in winter (or they whither but persist on the plant)
    Leaf form
    the leaves are green, with an expanded blade and a leaf-like texture
    Leaf hair orientation
    the hairs are flat against the leaf surface, mostly pointing towards the leaf tip
    Leaf shiny
    the upper side of the leaf is dull or slightly shiny
    Leaf spines
    there are no spines on the leaf edges
    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 base
    the petiole base clasps the stem or sheathes the stem
    Leaf teeth and lobes
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf 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)
    Leaf type
    the leaves are compound (made up of two or more discrete leaflets
    Leaf types
    NA
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    3
    Leaves per node
    there is one leaf per node along the stem
    Pinnately compound leaf type
    the pinnately compound leaves have a terminal leaflet (and usually have an odd number of leaflets per axis)
    Specific leaf type
    the leaf has a row of two or more lobes on each side of the central axis
    Stipels
    the petiolules have stipels at their bases
    Stipule features
    NA
    Stipule shape
    • the stipules are lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the stipules are ovate (widest below the middle and broadly tapering at both ends)
    Stipules
    the plant has stipules
    Teeth per side of leaf blade
    0

  • Place

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

  • Stem, shoot, branch

    Branched tendrils
    NA
    Direction of stem hairs
    • the hairs are pressed flat against the plant, pointing towards the plant's tip
    • the hairs point mostly upwards to outwards
    Hair between stem nodes
    the stem has hairs between the nodes
    Hairs between stem nodes
    the hairs on the stem are plain, without glands or branches, and not tangled
    Hooked hairs on stem between nodes
    no
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Plant height
    Up to 150 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem hair distribution
    the hairs on the stem are distributed more of less uniformly
    Stem nodes swollen
    the stem is not swollen at the nodes
    Stem orientation
    the stems trail at the base, but may turn upwards at the tips
    Stem roughness between nodes
    the stem does not feel rough
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils
    Wings on stem
    the stem does not have wings on it

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)
Massachusetts
widespread (S-rank: S5)

From Flora Novae Angliae dichotomous key

1.  Amphicarpaea bracteata (L.) Fern. N

American hog-peanut. Amphicarpaea bracteata (L.) Fern. var. comosa (L.) Fern.; A. comosa (L.) G. Don; A. monoica (L.) Ell.; A. pitcheri Torr. & Gray; Falcata comosa (L.) Kuntze; Glycine bracteata L.; G. comosa L. • CT, MA, ME, NH, RI, VT. Mesic forests, clearings, and shaded roadsides. Amphicarpaea bracteata is sometimes divided into two species— A. bracteata, the slender form with smaller leaflets and white to light purple corollas, and A. comosa, the robust form with larger leaflets and purple corollas. Turner and Fearing (1964) showed that too many intermediate forms exist to regard these as separate taxa.

Native to North America?

Yes

Sometimes confused with

Phaseolus polystachios:
flower stalks with bracts that are pointed at the apex, lower petal of flower arching upward in and inward toward center of flower (vs. A. bracteata, with the flower stalks with bracts that are blunt at the apex, lower petal of flower relatively straight).

Synonyms

  • Amphicarpaea bracteata var. comosa (L.) Fern.
  • Amphicarpaea comosa (L.) G. Don
  • Amphicarpaea monoica (L.) Ell.
  • Amphicarpaea pitcheri Torr. & Gray
  • Falcata comosa (L.) Kuntze
  • Glycine bracteata L.
  • Glycine comosa L.

Family

Fabaceae

Genus

Amphicarpaea