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Callitriche heterophylla — greater water-starwort

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Facts

Greater water-starwort is a common and widely-distributed species. The specific name (heterophylla) refers to the fact that submersed, floating and emersed leaves have very different morphologies. 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), 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
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf position
  • some of the leaves are floating at the surface of the water
  • the leaves are all submerged underwater
Leaf arrangement
opposite: there are two leaves per node along the stem
Leaf blade length
5–25 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
  • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
  • the leaf blade is triangular, with the stalk or attachment point on one of the sides
Underwater leaf blade width
Up to 10 mm
Fruit type (general)
the fruit is dry but does not split open when ripe
Underwater leaf length
5–25 mm
Show all characteristics

  • Clonal plantlets

    Turion length
    0 mm

  • Flowers

    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 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
    1–6 mm
    Style number
    2

  • Fruits or seeds

    Fruit length
    1–1.4 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
    0.6–1.2 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
    • the plant lives only a single year or less
    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
    Bracts
    the flowers or their pedicels have bracts at their bases
    Floating leaf basal lobes
    no
    Floating leaf blade width
    0–5 mm
    Floating leaf shape
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is triangular, with the stalk or attachment point on one of the sides
    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
    Floral bract length
    0.5–1.5 mm
    Leaf arrangement
    opposite: there are two leaves per node along the stem
    Leaf blade length
    5–25 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
    Up to 10 mm
    Leaf position
    • some of the leaves are floating at the surface of the water
    • 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 spatulate (spoon-shaped; narrow near the base, then suddenly widening to a rounded tip)
    Underwater leaf blade veins
    1
    Underwater leaf blade width
    Up to 10 mm
    Underwater leaf length
    5–25 mm
    Underwater leaf stalk
    no
    Underwater leaf tip shape
    the tip of the underwater leaf is rounded, with no point
    Veins in floating leaf
    3–5

  • Place

    Habitat
    aquatic
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • in lakes or ponds
    • in rivers or streams

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.

Maine
rare (S-rank: S2), special concern (code: SC)
Vermont
rare (S-rank: S2)

var. heterophylla

Massachusetts
widespread (S-rank: S5)

Subspecies and varieties

Our variety is Callitriche heterophylla Pursh var. heterophylla.

From Flora Novae Angliae dichotomous key

2.  Callitriche heterophylla Pursh var. heterophylla N

greater water-starwort. Callitriche anceps Fern. • CT, MA, ME, NH, RI, VT. Shallow, still or 
slow-moving water of rivers, lakes, and pools, ascending to high elevation in NH and VT. Callitriche anceps was originally believed to be a wholly submersed, boreal species allied 
to C. heterophylla. The characteristics used by Fernald (1950b) to distinguish Callitriche anceps from C. heterophylla (e.g., stem width and length, fruit length, leaf blade morphology) are not diagnostic. Fassett (1951) commented on the lack of utility of these characteristics. However, Fassett maintained C. anceps on the basis of a very minor difference in fruit shape, though he noted that intermediates existed. It is here treated as part of the variation displayed by C. heterophylla.

Native to North America?

Yes

Sometimes confused with

Callitriche palustris:
fruit 0.2 mm or more longer than side, the apical portion of each half with a thin wing and an evident groove between the two haves (vs. C. heterophylla, with the fruit about as wide as long, lacking a thin wing, without or with a shallow groove between the two halves).

Synonyms

  • Callitriche anceps Fern.

Family

Plantaginaceae

Genus

Callitriche