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Hydrocharis morsus-ranae — European frog's-bit

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Facts

European frog's-bit is a Eurasian visitor, first planted in an arboretum pond in Ottawa, Canada in 1932 and subsequently invading the St. Lawrence River. It is now occasionally collected in Vermont lakes, river bays and side channels of rivers.

Habitat

Lacustrine (in lakes or ponds), riverine (in rivers or streams)

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
New England state
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
12–60 mm
Petal or sepal number
there are three petals, sepals, or tepals in the flower
Petal color
  • pink
  • 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 cordate (heart-shaped with backward-facing rounded lobes)
  • the leaf blade is orbicular (roughly circular, as wide as long)
  • the leaf blade is reniform (kidney-shaped; wider than long, with a basal sinus)
Underwater leaf blade width
0 mm
Fruit type (general)
  • the fruit is dry and splits open when ripe
  • the fruit is fleshy
Underwater leaf length
0 mm
Show all characteristics

  • Flowers

    Anther color
    there is a noticeable pink, reddish or purplish tint to the anthers
    Anther length
    Up to 1 mm
    Carpels fused
    the carpels are fused to one another
    Flower lower lip length
    0 mm
    Flower number
    1–5
    Flower position
    the flowers are above the surface of the water
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Inflorescence type
    • the inflorescence has only one flower on it
    • the inflorescence is a monochasial cyme (an axis with a terminal flower, below it a branch with a terminal flower, this branch may itself have a branch and so on)
    Length of flower stalk
    0–90 mm
    Length of peduncle
    Up to 50 mm
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    6
    Ovary position
    the sepals and/or petals are attached above 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
    • pink
    • white
    Petal fringed edges
    the petals are not fringed
    Petal fusion
    the perianth parts are separate
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal length
    Up to 10 mm
    Petal number
    3
    Petal or sepal number
    there are three petals, sepals, or tepals in the flower
    Pistil number
    1
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal number
    3
    Sepals fused only to sepals
    the sepals are separate from one another
    Spur length
    0 mm
    Stamen number
    • 10
    • 11
    • 12
    • 9
    Stamen position relative to petals
    NA
    Stamens fused
    • the stamens are fused to one another at or near their bases
    • the stamens are not fused to one another
    Stamens fused to petals
    the stamens are not fused to the petals or tepals
    Style length
    Up to 4 mm
    Style number
    6

  • Fruits or seeds

    Fruit type (general)
    • the fruit is dry and splits open when ripe
    • the fruit is fleshy
    Fruit type (specific)
    the fruit is a berry (fleshy, with the wall enclosing one or more sections, with two or more seeds)

  • Glands or sap

    Oil glands on nodes
    none of the nodes have oil glands
    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
    Roots floating in water
    there are no clusters of roots floating in the water
    Turions
    the plant has turions

  • Leaves

    Bract position (Sparganium)
    NA
    Bracts
    the flowers or their pedicels have bracts at their bases
    Floating leaf basal lobes
    no
    Floating leaf blade width
    13–63 mm
    Floating leaf length
    12–60 mm
    Floating leaf shape
    • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes)
    • the leaf blade is orbicular (roughly circular, as wide as long)
    • the leaf blade is reniform (kidney-shaped; wider than long, with a basal sinus)
    Floating leaf tip
    • the tip of the floating leaf blade is obtuse (bluntly pointed)
    • the tip of the floating leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
    Floral bract form
    the bracts are roughly as lobed as the foliage leaves
    Leaf arrangement
    basal: the leaves are growing only at the base of the plant
    Leaf blade length
    12–60 mm
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    13–63 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
    Trap-bladder length
    0 mm
    Underwater leaf air passage number
    At least 1440
    Underwater leaf air passage relative width
    At least 1442
    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
    yes
    Underwater leaf stalk length
    40–60 mm
    Underwater leaf tip shape
    NA

  • Place

    Habitat
    aquatic
    New England state
    Vermont
    Specific habitat
    • in lakes or ponds
    • in rivers or streams

  • 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
absent
Maine
present, prohibited
Massachusetts
absent
New Hampshire
absent
Rhode Island
absent
Vermont
present, invasive, prohibited

Conservation status

None

From Flora Novae Angliae dichotomous key

1.  Hydrocharis morsus-ranae L. E

European frog’s-bit. ME, VT. Lakes, embayments and side channels of rivers.

Native to North America?

No

Sometimes confused with

Heteranthera reniformis:
leaves of two types--petiolate with cordate to reniform blades and sessile with linear blades, and flowers zygomorphic, the uppermost petal with a green spot (vs. H. morsus-ranae, with leaves of one type--petiolate with cordate to reniform blades, and flowers actinomorphic, none of the petals with a green spot).
Limnobium spongia:
primary lateral veins of leaves diverging from midvein at an angle of 30-80 degrees and floating leaf blades with conspicuous aerenchyma tissue extending nearly the entire width on the abaxial surface (vs. H. morsus-ranae, with primary lateral veins of leaves diverging from midvein at an angle of 75-90 degrees and all leaves having aerenchyma tissue confined to each side of the midrib on the abaxial surface).

Family

Hydrocharitaceae

Genus

Hydrocharis