Astragalus alpinus L.

alpine milk-vetch

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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

Alpine milk-vetch has a circumboreal distribution, and is found across northern North America. In New England it is rare and occurs in Maine, New Hampshire and Vermont on open river shores on high-pH, rocky or gravel substrate.

Habitat

Shores of rivers or lakes

Characteristics

Habitat
wetlands
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
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
8–16 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 length
    7–13 mm
    Flower number
    5–15
    Flower orientation
    the flower points upwards or is angled outwards
    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
    Fusion of sepals and petals
    the petals or the sepals are fused into a cup or tube
    Hairs on inflorescence
    the axis of the inflorescence has hairs entirely without glands
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower has a hypanthium
    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
    Length of flower stalk
    0.5–1.5 mm
    Length of peduncle
    30–150 mm
    Marks on petals
    the petals have spots or streaks on them
    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
    Number of styles
    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 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 folding in bud
    • the petals in bud are arranged in a cycle with edges overlapping like roof shingles (imbricate)
    • the petals in bud meet exactly at the margins without overlapping (valvate)
    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
    7–13 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)
    Petal tip shape
    the petal tip is retuse (with a blunt or rounded apex and a notch at the center)
    Petal tips (Cuscuta)
    NA
    Petal width
    3–7.5 mm
    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 auricles
    the sepals have no auricles
    Sepal color
    green to brown
    Sepal length
    4–6 mm
    Sepal number
    4–5
    Sepal orientation
    the sepals are pressed against the corolla, or jutting stiffly upward
    Sepal relative length
    the sepal lobes are shorter than the fused portion
    Sepal shape
    the sepal outline is roughly triangular
    Sepal texture
    the sepals are either very thin but flexible, like a membrane, or they are leaf-like in texture
    Sepal tip shape
    the sepal tip is acute (is sharply pointed)
    Sepal uniformity
    one or more of the sepals is much narrower or shorter than the others
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    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
    Fruit (pyxis) dehiscence
    NA
    Fruit cross-section
    the fruit is roughly triangular in cross-section
    Fruit features (Brassicaceae)
    NA
    Fruit length
    8–16 mm
    Fruit length relative to sepals
    the fruit is longer than its associated sepals
    Fruit locules
    one
    Fruit shape
    • the fruit is ellipsoid (widest in the middle and tapering to each end)
    • the fruit is obloid (longer than wide and with rounded ends)
    Fruit stalk orientation
    • the fruits curve or droop downwards
    • 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 legume (a fruit that splits into two valves, but only has a single carpel; think of a pea pod)
    Fruit width
    3–4 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 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
    1.5–3.5 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 length
    2.5–3 mm
    Seed number
    5–10
    Seed relative length
    the seed is longer than it is wide
    Seed surface
    the seed is smooth or without clear markings
    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 an herb (it has self-supporting stems)
    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
    there are spines on the plant
    Underground organs
    the plant has a caudex (the root mass is firm and hardened at the top)
  • 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 to width ratio (compound lvs only)
    1.3–3.5
    Floral bracts
    the flower has one or more bracts associated with it
    Flower bract length
    0.5–2 mm
    Hairs on leaf stalk
    the petiole has hairs on 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
    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 no stalk
    Leaf blade base shape
    the base of the leaf blade is rounded
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    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 length
    20–80 mm
    Leaf blade primary vein pattern
    the secondary veins branch off at intervals from the primary vein
    Leaf blade shape
    the leaf blade is elliptic (widest near the middle and tapering at both ends)
    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 veins
    the leaf blade has one main vein running from the base towards the tip (it may or may not have secondary veins)
    Leaf blade width
    2–7 mm
    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
    NA
    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 is narrow where it attaches to the stem
    Leaf stalk length
    30–120 mm
    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 retuse (blunt or rounded, with a notch at the tip)
    • the tip of the leaf blade is rounded, with no point
    Leaf type
    the leaves are compound (made up of two or more discrete leaflets
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    15–25
    Leaflet petiolules
    the leaflets of the compound leaf lack petiolules
    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
    there are no stipels at the bases of the petiolules
    Stipule features
    NA
    Stipule fused to leaf stalk
    the stipules are fused to the petioles for some or most of their length
    Stipule length
    1.5–6 mm
    Stipules
    the plant has stipules
  • Place
    Habitat
    wetlands
    Specific habitat
    shores of rivers or lakes
  • Stem, shoot, branch
    Branched tendrils
    NA
    Direction of stem hairs
    NA
    Hair between stem nodes
    the stem has no hairs between the nodes
    Hairs between stem nodes
    the stem has no hairs between the nodes
    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
    0.5–10 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem hair distribution
    NA
    Stem orientation
    • the stems are upright or angled outwards
    • the stems trail at the base, but may turn upwards at the tips
    Stem roughness between nodes
    the stem does not feel rough
    Stem spacing
    the plant is growing in tufts, or compact clusters with closely spaced stems, or it is densely matted together in clumps, cushionlike
    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)

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Maine
uncommon (S-rank: S3)

var. brunetianus

Maine
uncommon (S-rank: S3), special concern (code: SC)
New Hampshire
extirpated (S-rank: SX), X (code: X)
Vermont
extirpated (S-rank: SX)

Native to North America?

Yes

Sometimes Confused With

Astragalus eucosmus:
principal leaves with mostly 7-15 leaflets, keel petal markedly shorter than the banner petal, and upper suture of fruit scarcely sulcate (vs. A. alpinus, with principal leaves with 15-25 leaflets, keel petal not or only slightly shorter than the banner petal, and upper suture of fruit prominently sulcate).
Astragalus robbinsii:
principal leaves with mostly 7-15 leaflets, keel petal markedly shorter than the banner petal, and upper suture of fruit scarcely sulcate (vs. A. alpinus, with principal leaves with 15-25 leaflets, keel petal not or only slightly shorter than the banner petal, and upper suture of fruit prominently sulcate).

Synonyms

  • Astragalus alpinus L. var. labradoricus (DC.) Fern.

Family

Fabaceae

Genus

Astragalus

Notes on Subspecies and Varieties in New England

Our variety is Astragalus alpinus L. var. brunetianus Fern.

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Information from Dichotomous Key of Flora Novae Angliae

1.  Astragalus alpinus L. var. brunetianus Fern. NC

alpine milk-vetch. Astragalus alpinus L. var. labradoricus (DC.) Fern. • ME, NH, VT. Open, gravel, cobble, and ledge river shores in regions of high-pH bedrock and/or till.