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Native Plant Trust: Go Botany Discover thousands of New England plants

Phaseolus polystachios — wild bean

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Facts

Wild bean is native to southern and eastern North America, reaching the northern limit of its distribution as it enters southern New England. This is the only member of the bean genus (Phaseolus) native to North America. The seeds are edible, and remains have been recovered from prehistoric archaeological sites.

Habitat

Cliffs, balds, or ledges, forests, talus and rocky slopes, woodlands

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
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 has lobes, or it has both teeth and lobes
  • 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
Stamen number
10
Fruit type (general)
the fruit is dry but does not split open when ripe
Fruit length
30–60 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
    Calyx symmetry
    there is only one way to evenly divide the calyx (the calyx is bilaterally symmetrical)
    Carpels fused
    • NA
    • the carpel is solitary or (if 2 or more) the carpels are not fused to one another
    Cleistogamous flowers
    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 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 narrow at the tip and unbranched
    Fused stamen clusters
    there are two clusters of fused stamens
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower has a hypanthium
    Inflorescence length
    5–30 mm
    Inflorescence one-sided
    the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
    Inner tepals (Rumex)
    NA
    Nectar spur
    the flower has no nectar spurs
    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
    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 and sepal colors
    • blue to purple
    • white
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal folding in bud
    the petals in bud are arranged in a cycle with edges overlapping like roof shingles (imbricate)
    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 length
    9–11 mm
    Petal number
    5
    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 appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal length
    3–4 mm
    Sepal number
    5
    Sepal relative length
    the sepal lobes are shorter than the fused portion
    Sepal uniformity
    all the sepals are about the same size
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    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 in another position
    • the stigmas are positioned at the tip of the style
    • the stigmas are positioned on the inner surface 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
    Fruit (pyxis) dehiscence
    NA
    Fruit cross-section
    the fruit is at least somewhat flattened
    Fruit features (Brassicaceae)
    NA
    Fruit length
    30–60 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 but does not split 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
    7–10 mm
    Hair type on fruit
    NA
    Hairs on fruit
    the fruits are not hairy
    Legumes (Fabaceae)
    the legume has none of the mentioned special features
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit has a stipe
    Ovary stipe length
    2–3 mm
    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
    At least 2
    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 more than two years
    Parasitism
    the plant is not parasitic
    Plant color
    the leaves or young stems of the plant are green
    Plants darken when dry
    no
    Spines on plant
    the plant has no spines
  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracteoles
    the plant has bracteoles between the primary bracts and the flowers
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    30–100 mm
    Final leaf segment length to width ratio (compound lvs only)
    1–1.4
    Floral bracts
    the flower has one or more bracts associated with it
    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
    • the upper side of the leaf is not hairy, or it has very few hairs
    Hooked hairs on underside of leaf
    yes
    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
    Leaf blade edges
    • the edge of the leaf blade has lobes, or it has both teeth and lobes
    • the edge of the leaf blade is entire (has no teeth or lobes)
    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 veins
    the leaf blade has one main vein running from the base towards the tip (it may or may not have secondary veins)
    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 spines
    there are no spines on the leaf edges
    Leaf stalk
    the leaves have leaf stalks
    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)
    Leaf type
    the leaves are compound (made up of two or more discrete leaflets
    Leaf types
    There is a gradual change in appearance of the leaves from the base (or near the base) of the plant to those from further up on the stem, with leaves progressively changing as one moves higher on the stem (often becoming shorter, or less toothed/lobed, and/or with shorter petioles).
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    1–4
    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
    Stipules
    the plant has stipules
    Teeth per side of leaf blade
    0
  • Place

    Habitat
    terrestrial
    Specific habitat
    • cliffs, balds, or ledges
    • forests
    • talus or rocky slopes
    • woodlands
  • Scent

    Plant odor
    the plant does not have much of a smell
  • Stem, shoot, branch

    Branched tendrils
    NA
    Flowering stem cross-section
    • the flowering stem has strong or sharp angles, but is not square
    • the flowering stem is circular, or with lots of small angles so that it is roughly circular
    Hair between stem nodes
    the stem has hairs between the nodes
    Hooked hairs on stem between nodes
    yes
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Plant height
    Up to 600 cm
    Stem orientation
    • NA
    • the stems are upright or angled outwards
    • the stems trail at the base, but may turn upwards at the tips
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils

Wetland status

Not classified

In New England

Distribution

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

Conservation status

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

Connecticut
unranked (S-rank: SNR)

var. polystachios

Connecticut
historical (S-rank: SH), special concern, extirpated (code: SC*)

From Flora Novae Angliae dichotomous key

2.  Phaseolus polystachios (L.) B.S.P. NC

wild bean. Dolichos polystachyus L.; Phaseolus polystachios (L.) B.S.P. var. aquilonius Fern.; 
 P. smilacifolius Pollard • CT. Also reported from ME by Gleason (1963) and RI by George (1992), but specimens are unknown. Rocky forests and woodlands, cliff bases. The report for ME by Gleason (1963) is almost certainly in error given that this species is not known north of CT based on specimens that have been examined.

Native to North America?

Yes

Sometimes confused with

Phaseolus vulgaris:
inflorescence with a stout, relatively straight axis, legumes longer than 8 cm, and plants annual (vs. P. polystachios, with the inflorescence with a slender, flexuous axis, legumes 3–6 cm long, and plants perennial).

Synonyms

  • Dolichos polystachyus L.
  • Phaseolus polystachios (L.) B.S.P. var. aquilonius Fern.
  • Phaseolus smilacifolius Pollard

Family

Fabaceae

Genus

Phaseolus