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Callitriche hermaphroditica — autumn water-starwort

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Facts

Autumn water-starwort, an annual aquatic of shallow lake water, has a circumboreal distribution, but is rare and protected in New England, being found only in Lake Champlain, Vermont. Water starworts (Callitriche) are remarkable for having flowers able to be pollinated by wind when emergent (anemophily), by water when floating at the surface (epihydrophily), as well as when submerged (hypohydrophily).

Habitat

Lacustrine (in lakes or ponds)

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
  • Connecticut
  • Massachusetts
  • Vermont
Leaf position
the leaves are all submerged underwater
Leaf arrangement
opposite: there are two leaves per node along the stem
Leaf blade length
4–20 mm
Petal or sepal number
NA
Petal color
NA
Specific leaf type
the leaf is not divided, rather the blade is made up of one segment
Floating leaf shape
NA
Underwater leaf blade width
0.6–2.2 mm
Fruit type (general)
the fruit is dry but does not split open when ripe
Underwater leaf length
5.5–15.3 mm
Show all characteristics

  • Clonal plantlets

    Turion length
    0 mm

  • Flowers

    Anther length
    0.1–0.6 mm
    Carpels fused
    the carpels are fused to one another
    Flower lower lip length
    0 mm
    Flower number
    1
    Flower position
    the flowers are below the surface of the water
    Flower symmetry
    NA
    Inflorescence type
    • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
    • the inflorescence has only one flower on it
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    2
    Ovary position
    the sepals and/or petals are attached below the ovary
    Palate on corolla
    NA
    Petal and sepal arrangement
    the flower includes neither petals nor sepals
    Petal appearance
    NA
    Petal color
    NA
    Petal fringed edges
    NA
    Petal fusion
    NA
    Petal hairs on inner/upper surface
    NA
    Petal length
    0 mm
    Petal number
    0
    Petal or sepal number
    NA
    Pistil number
    1
    Sepal appearance
    NA
    Sepal length
    0 mm
    Sepal number
    0
    Sepals fused only to sepals
    NA
    Spur length
    0 mm
    Stamen length
    0.6–1.5 mm
    Stamen number
    1 or 2
    Stamen position relative to petals
    NA
    Stamens fused
    NA
    Stamens fused to petals
    • NA
    • the stamens are not fused to the petals or tepals
    Style length
    0.6–2.5 mm
    Style number
    2

  • Fruits or seeds

    Fruit length
    1–2 mm
    Fruit type (general)
    the fruit is dry but does not split open when ripe
    Fruit type (specific)
    the fruit is a schizocarp (when dry it splits into sections, each holding one or more seeds)
    Fruit width
    1.5–2.5 mm

  • 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
    there are no turions on the plant
    Underground organs
    there are only slender roots on the plant

  • Leaves

    Bract position (Sparganium)
    NA
    Bract relative length
    At least 3854 mm
    Bracts
    neither the flowers nor their pedicels have bracts
    Floating leaf basal lobes
    NA
    Floating leaf blade width
    0 mm
    Floating leaf length
    0 mm
    Floating leaf shape
    NA
    Floating leaf tip
    NA
    Floral bract form
    NA
    Floral bract length
    0 mm
    Leaf arrangement
    opposite: there are two leaves per node along the stem
    Leaf blade length
    4–20 mm
    Leaf blade veins
    the lateral veins radiate from the base and continue to spread away from the centerline of the leaf, or branch off the central vein at intervals
    Leaf blade width
    0.6–2.2 mm
    Leaf position
    the leaves are all submerged underwater
    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
    the underwater leaf has smooth edges, without teeth
    Underwater leaf blade shape
    • the underwater leaf blade is linear (very narrow with more or less parallel sides)
    • the underwater leaf blade is oblong (rectangular but with rounded ends)
    Underwater leaf blade veins
    1
    Underwater leaf blade width
    0.6–2.2 mm
    Underwater leaf length
    5.5–15.3 mm
    Underwater leaf stalk
    no
    Underwater leaf tip shape
    • the tip of the underwater leaf is retuse (blunt or rounded, with a notch at the tip)
    • the tip of the underwater leaf is rounded, with no point
    Veins in floating leaf
    0

  • Place

    Habitat
    aquatic
    New England state
    • Connecticut
    • Massachusetts
    • Vermont
    Specific habitat
    in lakes or ponds

  • Stem, shoot, branch

    Flowering stem growth form
    the flowering stem trails along the substrate, or floats in the water

Wetland status

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

In New England

Distribution

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

Conservation status

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

Vermont
historical (S-rank: SH)

From Flora Novae Angliae dichotomous key

1.  Callitriche hermaphroditica L. NC

autumn water-starwort. Callitriche autumnalis L. • CT, MA, VT, most collections within Lake Champlain. Shallow water of lakes and rivers. Callitriche hermaphroditica is unique among New England members of this genus in having distinct leaves and lacking leaf scales (the remaining species have leaves at each node with connate bases and leaf blades that appear minutely punctate due to the presence of leaf scales).

Native to North America?

Yes

Sometimes confused with

Callitriche stagnalis:
leaves dimorphic, the floating ones with 5-7 veins by branching of the lateral veins, and flowers and fruits subtended by 2 white or translucent bracts (vs. C. hermaphroditica, with leaves monomorphic, all with 1 vein, and flowers and fruits without subtending bracts).
Callitriche terrestris:
fruit 0.5-0.7 mm long, borne on a short pedicel 0.1-0.6 mm long, each half of the fruit with an inconspicuous wing-margin, and leaf blades 2-5 mm long (vs. C. hermaphroditica, with fruit 1-2 mm long, subsessile, each half of the fruit with an conspicuous wing-margin, and leaf blades mostly 4-15 mm long).

Synonyms

  • Callitriche autumnalis L.

Family

Plantaginaceae

Genus

Callitriche