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Alisma subcordatum — southern water-plantain

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Facts

Southern water-plantain is found in marshes, ditches, and shallow lakes and streams. The Cherokee used it to make a topical aid for sores, wounds, bruises, swelling, and ulcers, and the Cree took the stem base internally to treat stomach and bowel conditions.

Habitat

Anthropogenic (man-made or disturbed habitats), lacustrine (in lakes or ponds), marshes, riverine (in rivers or streams), shores of rivers or lakes, wetland margins (edges of wetlands)

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf position
some of the leaves are floating at the surface of the water
Leaf arrangement
basal: the leaves are growing only at the base of the plant
Leaf blade length
Up to 150 mm
Petal or sepal number
there are three petals, sepals, or tepals in the flower
Petal color
white
Specific leaf type
the leaf is not divided, rather the blade is made up of one segment
Floating leaf shape
  • the leaf blade is elliptic (widest near the middle and tapering at both ends)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
Underwater leaf blade width
0 mm
Fruit type (general)
the fruit is dry but does not split open when ripe
Underwater leaf length
0 mm
Show all characteristics

  • Clonal plantlets

    Turion length
    0 mm

  • Flowers

    Anther color
    there is a noticeable pink, reddish or purplish tint to the anthers
    Anther length
    0.4–0.6 mm
    Carpels fused
    the carpel is solitary or (if 2 or more) the carpels are not fused to one another
    Flower lower lip length
    0 mm
    Flower position
    • the flowers are above the surface of the water
    • the flowers are below the surface of the water
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Inflorescence length
    Up to 1000 mm
    Inflorescence type
    the inflorescence is a panicle (branched, with the individual flowers on stalks)
    Length of peduncle
    Up to 600 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    At least 3
    Ovary position
    the sepals and/or petals are attached below the ovary
    Palate on corolla
    no
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal color
    white
    Petal fringed edges
    • the petals are fringed
    • the petals are not fringed
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal length
    1.8–2.5 mm
    Petal number
    3
    Petal or sepal number
    there are three petals, sepals, or tepals in the flower
    Pistil number
    6 or more
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal length
    1.5–6 mm
    Sepal number
    3
    Spur length
    0 mm
    Stamen number
    6
    Stamen position relative to petals
    NA
    Stamens fused
    the stamens are not fused to one another
    Stamens fused to petals
    the stamens are not fused to the petals or tepals
    Style length
    0.2–0.4 mm
    Style number
    15–20

  • Fruits or seeds

    Fruit length
    1.5–2.2 mm
    Fruit type (general)
    the fruit is dry but does not split open when ripe
    Fruit type (specific)
    the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)

  • Glands or sap

    Oil glands on nodes
    none of the nodes have oil glands
    Sap
    the sap is milky and opaque, and may be white or colored

  • Growth form

    Lifespan
    the plant lives more than two years
    Root septa
    the roots do not have transverse septa
    Roots floating in water
    there are no clusters of roots floating in the water
    Turions
    there are no turions on the plant
    Underground organs
    the plant has a rhizome (a horizontal underground stem with roots growing from it)

  • Leaves

    Bract position (Sparganium)
    NA
    Bract relative length
    At least 1379 mm
    Bracts
    the flowers or their pedicels have bracts at their bases
    Floating leaf basal lobes
    no
    Floating leaf blade width
    20–120 mm
    Floating leaf length
    0 mm
    Floating leaf shape
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    Floating leaf tip
    • the tip of the floating leaf blade is acute (sharply pointed)
    • the tip of the floating leaf blade is obtuse (bluntly pointed)
    Floral bract form
    the bracts are roughly as lobed as the foliage leaves
    Floral bract length
    Up to 10 mm
    Leaf arrangement
    basal: the leaves are growing only at the base of the plant
    Leaf blade length
    Up to 150 mm
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    20–120 mm
    Leaf position
    some of the leaves are floating at the surface of the water
    Leaf special features
    none of the mentioned special features are present
    Leaf-like branch segments
    0
    Leaf-like branch shape
    NA
    Specific leaf type
    the leaf is not divided, rather the blade is made up of one segment
    Staminate bract edge (Myriophyllum)
    NA
    Stipule appearance
    NA
    Stipule fused to leaf
    NA
    Stipules
    there are no stipules on the plant
    Stipules fused around stem
    NA
    Trap-bladder length
    0 mm
    Underwater leaf blade edges
    NA
    Underwater leaf blade shape
    NA
    Underwater leaf blade veins
    0
    Underwater leaf blade width
    0 mm
    Underwater leaf length
    0 mm
    Underwater leaf stalk
    NA
    Underwater leaf stalk length
    0 mm
    Underwater leaf tip shape
    NA
    Veins in floating leaf
    0

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of wetlands
    • in lakes or ponds
    • in rivers or streams
    • man-made or disturbed habitats
    • marshes
    • shores of rivers or lakes

  • Stem, shoot, branch

    Flowering stem growth form
    the flowering stem is upright

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

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.

Massachusetts
widespread (S-rank: S5)

From Flora Novae Angliae dichotomous key

2.  Alisma subcordatum Raf. N

southern water-plantain. Alisma plantago-aquatica L. var. parviflorum (Pursh) Torr.; A. plantago-aquatica L. ssp. subcordatum (Raf.) Hultén • CT, MA, ME, NH, RI, VT. Marshes, muddy shorelines, ditches, and shallow, circumneutral to slightly basic water of lakes and slow-moving streams.

Native to North America?

Yes

Sometimes confused with

Alisma triviale:
petals conspicuously longer than the sepals and fruits 1.8-3 mm long (vs. A. subcordatum, with petals +/- as long as the sepals and fruits 1.5-2.2 mm long).

Synonyms

  • Alisma plantago-aquatica L. ssp. subcordatum (Raf.) Hultén
  • Alisma plantago-aquatica L. var. parviflorum (Pursh) Torr.

Family

Alismataceae

Genus

Alisma